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United  States  Steel  Corporation 

METHODS    FOR    THE   TECHNICAL 
SAMPLING  AND  ANALYSIS  OF  GASES 


THE  METHODS 


OF  THE 


UNITED  STATES  STEEL  CORPORATION 


FOR    THE 


TECHNICAL  SAMPLING  AND  ANALYSIS 
OF  GASES 


COPYRIGHT   1918, 

BY 

J.   M.  CAMP, 

CHAIRMAN  CHEMISTS'  COMMITTEE, 

UNITED  STATES  STEEL  CORPORATION, 

CARNEGIE  BUILDING,  PITTSBURGH  PENNA, 


PREFACE  TO  THE  SECOND  EDITION. 

The  interval  since  the  publication  of  the  first  edition  of  this  pamphlet  has 
proved  to  be  a  period  of  notable  industrial  progress,  and  this  statement  is  par- 
ticularly applicable  to  the  maufacture  and  use  of  by-product  coke  oven  gas. 
This  fact  made  the  enlargement  and  revision  of  the  pamphlet  very  desirable 
while  the  success  and  consequent  exhaustion  of  che  first  edition  made  the 
preparation  of  a  new  edition  necessary  to  meet  the  demands  for  copies  of  the 
book.  Except  for  changes  in  the  phraseology,  the  methods  of  the  first  edition 
for  the  analysis  of  the  gases  treated  therein  have  been  retained  with  but  few 
changes  of  real  importance.  The  use  of  a  10%  sodium  chloride  solution  for 
sampling  is  recommended,  and  the  measuring  burette  has  been  graduated  and 
marked  to  read  from  the  top  downward  instead  of  from  the  bottom  upwaid, 
but  it  is  evident  that  these  changes  affect  the  methods  but  slightly.  As  to  the 
additions  to  the  text,  the  method  for  the  analysis  of  by-product  gas  is  made  as 
nearly  as  possible  like  that  for  producer  and  blast  furnace  gases,  but  a  method 
for  the  analysis  of  natural  gas  has  been  incorporated  that  differs  slightly  from 
that  given  for  other  fuel  gases  in  that  larger  quantities  for  explosion  are 
employed.  This  feature  of  the  method  is  of  decided  advantage,  because  no 
error  is  introduced  by  the  high  percentage  of  resulting  carbon  dioxide. 

The  committee  appointed  for  the  preparation  of  this  revised  edition  of 
the  gas  pamphlet  was  composed  of  the  following  gentlemen:  Mr.  W.  D.  Brown, 
Chemist  of  the  Duquesne  Works,  Carnegie  Steel  Company;  Dr.  J.  R.  Harris, 
Chemist  of  the  Tennessee  Coal,  Iron  and  Railroad  Company;  and  Mr.  J.  V. 
Freeman,  Chemist  of  the  Central  Laboratory,  Joliet  Works,  Illinois  Steel 
Company. 


PREFACE  TO  THE  FIRST  EDITION. 

This  pamphlet  is  descriptive  of  the  methods  selected  by  the  chemists  of 
the  Corporation,  acting  through  the  Chemists'  Committee,  for  the  technical 
sampling  and  analysis  of  gases.  With  the  increased  significance  attached 
to  the  economic  control  of  those  industrial  processes  involving  the  combust- 
ion of  fuels  and  with  the  application  of  keen  scientific  research  to  the  various 
problems  involved,  it  becomes  readily  apparent  that  accurate  knowledge  of 
the  composition  of  the  gases  encountered  is  a  matter  of  prime  importance. 
This  fact  is  exemplified  by  the  rapid  increase  in  the  use  of  internal  combustion 
engines,  using  blast  furnace  or  producer  gas  as  a  fuel,  and  by  the  increasing 
necessity  for  greater  watchfulness  upon  the  efficiency  of  boilers,  stoves,  and 
furnaces.  The  need  is  obvious,  for  use  by  the  laboratories  of  the  United  States 
Steel  Corporation,  of  a  standard  system  of  sampling  and  analysis  of  gases,  in 
order  that  comparable  results  may  be  obtained  with  the  maximum  degree  of 
accuracy,  consistent  with  the  minimum  of  time  requisite  for  execution. 

This  description  was  consummated  through  a  review  of  the  practices, 
especially  written  for  this  purpose,  of  all  the  laboratories  of  the  Corporation 
engaged  in  the  sampling  and  analysis  of  gases.  The  apparatus  shown  for  the 
analysis  is  to  be  considered  only  as  a  type  of  the  permissible  form.  The  essen- 
tial points  are  the  exclusive  use  of  the  capillary  tubes,  the  permanency  of 
connection  of  the  auxiliary  gases,  compactness,  and  the  applicability  of  the 
apparatus  to  the  accompanying  description.  This  form  of  apparatus  and  the 
methods  as  here  described  are  to  take  precedence  over  all  others  employed 
for  the  analysis  of  gases  throughout  the  laboratories  of  the  Corporation. 

It  is  the  desire  of  the  Chemists'  Committee  here  to  acknowledge  their 
grateful  appreciation  of  the  services  of  Mr.  D.  A.  Barkley  and  Mr.  R.  J. 
Wysor,  assistants  in  the  Duquesne  Laboratory,  in  the  preparation  of  this 
pamphlet. 

THE  CHEMISTS'  COMMITTEE. 


INTRODUCTION. 


INTRODUCTION. 

In  the  preparation  of  the  accompanying  standard  methods  for  the  samp- 
ling and  analysis  of  gases,  there  has  been  an  unwavering  purpose  to  eliminate, 
so  far  as  possible,  tedious  analytical  procedure  and  the  use  of  cumbersome 
forms  of  apparatus.  It  has  been  desired  to  adopt  methods,  inherently  correct 
in  principle,  which,  in  conjunction  with  simplified  apparatus,  will  insure  the 
requisite  expediency,  at  times  so  necessary  in  commercial  work,  without  an 
appreciable  sacrifice  in  accuracy  of  results.  While  no  notable  originality  is 
claimed  in  general  for  the  subject  matter  of  this  pamphlet,  it  is  believed  that 
the  application  of  well  known  methods,  coupled  with  certain  novel  features 
in  execution  and  in  the  forms  of  apparatus  used,  will  be  presented.  No 
apology  is  offered  for  the  unabridged  nature  of  the  descriptions  and  explana- 
tions appearing  in  this  pamphlet.  The  delineation  of  the  methods  has  been 
made  in  considerable  detail  so  as  to  be  clearly  intelligible  to  amateurs  as  well 
as  to  those  better  versed  in  the  subject. 


SAMPLING. 

It  is  impossible  within  the  compass  of  this  pamphlet  to  give  a  detailed 
method,  for  sampling  gases,  that  would  be  applicable  to  all  the  works  of  the 
Corporation  and  the  various  manufacturing  operations  therein.  It  is  preferred 
to  make  this  description  general,  leaving  to  each  individual  operator  the 
solution  of  the  details  to  meet  his  own  particular  conditions.  In  the  sampling  of 
gases  two  kinds  of  samples  are  recognized;  namely — the  accumulative  and  the 
control.  The  accumulative  comprises  all  samples  taken  continuously  during 
uninterrupted  periods  that  may  vary  from  one-half  to  twenty-four  hours,  and 
the  results  obtained  from  samples  taken  in  this  manner  will  constitute  the 
official  analysis,  that  is,  they  only  will  be  considered  in  making  comparisons 
with  like  results  from  other  works.  Under  the  head  of  the  control  samples 
are  included  all  those  samples  taken  for  a  shorter  period  of  time  than  the  mini- 
mum given  above,  and  will  represent  momentary  conditions  of  the  particular 
operation  in  question,  and  are  for  the  guidance  of  the  works  only.  All 
analytical  reports  shall  show  the  duration  of  the  time  of  sampling  in  order 
that  the  status  of  the  results  may  be  known. 


SAMPLING. 


SAMPLING. 


In  sampling  blast  furnace  or  producer  gases,  which  are  considered  homo- 
geneous in  the  cross  section  of  the  main,  the  gas  is  withdrawn  through  a  pet- 
cock  on  a  pipe  threaded  into  the  shell  of  the  main  and  extending  in  beyond  the 
brickwork  lining.  In  the  absence  of  lining  the  gas  may  be  withdrawn  through 
a  petcock  on  the  shell,  or  when  the  main  is  inaccessible,  on  a  pipe  leading  from 
the  main,  through  which  a  continuous  current  of  gas  passes. 

In  sampling  flue  gas  it  is  necessary  that  the  gas  be  withdrawn  through  a 
perforated  pipe,  which  enters  with  air-tight  connection  and  extends  entirely 
across  the  flue.  The  pipe  is  closed  at  the  anterior  end  and  provided  at  the 
outer  end  with  an  aspirating  device,  operated  by  air,  water,  or  steam  (see 
sketch).  The  perforations  in  this  pipe  should  be  equal  distances  apart,  and,  to 
obtain  an  equal  flow  through  all  openings,  their  combined  area  should  be  less 
than  the  cross  sectional  area  of  the  pipe,  three  to  four  being  considered  a  safe 
ratio.  The  sample  is  withdrawn  from  the  sampling  pipe  through  a  petcock 
situated  between  the  flue  and  the  aspirating  device.  This  pipe  may  also  be 
used  in  sampling  blast  furnace  or  producer  gas;  but,  instead  of  aspirating,  the 
gas  is  allowed  to  escape  under  its  own  pressure. 

An  apparatus  for  collecting  an  accumulative  sample  is  shown  in  the 
accompanying  photograph.  This  appliance  which  is  but  one  of  many  that  may 
be  used,  has  the  advantage  of  simplicity  of  construction  and  operation.  When 
a  sample  is  collected,  the  petcock,  permanently  attached  to  the  main,  the  flue 
or  the  intermediary  pipe  before  mentioned,  is  connected  by  a  rubber  tube 
with  one  hole  of  the  doubly  perforated  stopper  in  the  two  gallon  aspirator 
bottle.  This  aspirator  bottle  contains  a  10%  solution  of  sodium  chloride, 
which  has  been  saturated  with  the  gas  to  be  sampled.  The  lower  opening  of 
this  bottle  is  connected  by  a  rubber  tube  with  a  similar  opening  in  another 
bottle  placed  on  a  lower  level,  the  rate  of  flow  of  water  from  the  upper  to  the 
lower  bottle  being  controlled  by  a  screw  compressor.  The  petcock  being  open, 
the  compressor  is  released,  and  the  gas  rapidly  displaces  the  water  in  the 
upper  bottle.  On  closing  the  petcock,  reversing  the  bottles  and  opening  the 
pinchcock  on  the  rubber  tube  leading  from  the  second  hole  in  the  rubber 
stopper,  the  gas  is  rapidly  expelled  into  the  air  until  the  rubber  tube  constitut- 
ing the  exit  is  full  of  water.  The  pinchcock  is  closed,  the  bottles  reversed,  and 
the  upper  one  filled  with  gas,  the  rate  of  inflow  of  gas  being  so  controlled  by 
the  compressor  that  the  bottle  is  filled  in  the  designated  time,  varying  from 
one-half  to  twenty-four  hours  as  previously  stated. 


SAMPLING. 


APPARATUS  FOR  THE  SAMPLING  or  GASES. 


SAMPLING.  9 


A  portion  for  analysis  is  transferred  from  the  bottle  to  the  small  sample 
tube  (No.  2,  Analytical  Apparatus).  This  tube  may  be  of  glass  or  metal.  It 
is  approximately  two  inches  in  diameter  and  eight  inches  in  length,  with  a 
capacity  of  about  300  c.  c.  Its  ends  are  conically  shaped  and  are  terminated 
by  petcocks.  The  sample  tube,  including  the  upper  petcock,  is  filled  with 
a  10%  solution  of  sodium  chloride,  and  is  attached  to  the  rubber  tubing  con- 
stituting the  exit  from  the  gas  bottle,  which  is  also  full  of  the  solution.  The 
position  of  the  aspirator  bottles  is  reversed,  thus  placing  the  gas  under 
pressure,  the  pinchcock  is  opened,  the  upper,  then  the  lower  cocks  on  the 
sample  tube  are  opened,  and  the  gas  is  allowed  to  displace  the  solution  in  the 
tube  and  flow  through  for  a  short  time  to  saturate  the  moisture  adhering  to  the 
sides.  The  lower,  then  the  upper  cock  on  the  tube  is  closed,  leaving  the  gas 
under  slight  pressure.  The  sodium  chloride  solution  in  the  sample  tube  may 
be  used  repeatedly.  The  sample  is  delivered  to  the  laboratory  and  analyzed 
as  soon  as  possible.  To  prevent  entrance  of  air,  the  ends  of  the  tube  may  be 
dipped  in  molten  parafnne. 

When  desired,  a  gasometer  may  be  used  for  withdrawing  a  larger  sample 
of  such  size  that  calormetric  determinations  may  also  be  made.  If  uncleaned 
gas  is  to  be  sampled  continuously,  it  is  first  passed  through  a  suitable  filter  for 
removing  the  dust.  The  water  in  the  gasometer  is  used  continually  and  as 
long  as  practicable.  A  small  sample  for  analysis  is  forced  through  a  petcock 
on  the  holder  and  then  through  a  rubber  tubing  connection  into  the  sample 
tube  in  the  manner  previously  described. 

When  it  is  desired  to  obtain  a  control  sample,  representing  momentary 
conditions  in  the  main,  a  sample  tube  filled  with  water  or  sodium  chloride 
solution  is  connected  by  a  rubber  tube  to  the  petcock  on  the  main  or  intermed- 
iary pipe.  If  the  gas  be  under  pressure,  the  petcock,  the  upper,  then  the  lower 
cock  on  the  sample  tube  are  opened,  and  the  gas  is  allowed  to  displace  the 
water  and  flush  through.  If  the  gas  be  under  vacuum,  an  aspirator,  for  which 
another  sample  tube  answers  well,  is  connected  with  the  lower  end  of  the 
sample  tube.  With  both  vessels  filled  with  water,  the  cocks  are  opened,  and 
the  gas  is  drawn  into  the  sample  tube. 


10 


APPARATUS 


APPARATUS  FOR  THE  ANALYSIS  OF  GASES. 


APPARATUS.  11 


ANALYSIS. 

THE  APPARATUS. 

The  apparatus  shown  in  the  accompanying  photograph  has  been  designed 
with  particular  reference  to  its  adaptation  to  the  methods  subsequently  des- 
cribed. The  distinguishing  features  in  its  design  are  the  capillary  tube  of 
1  mm.  bore,  the  accessibility  of  the  auxiliary  gases,  oxygen  and  hydrogen,  and 
the  central  location  of  the  burette  in  the  apparatus,  thus  decreasing  the  error 
due  to  the  capillary  space.  Drawings  of  this  apparatus,  which  have  been 
copyrighted,  have  been  supplied  to  Messrs.  Eimer  and  Amend  of  New  York, 
the  authorized  makers,  who  are  prepared  to  supply  it  in  whole  or  in  part. 

The  general  disposition  of  the  apparatus  is  obvious.  On  the  extreme  left 
end  of  the  capillary  is  placed  the  rubber  tubing  connection  leading  to  the  Kipp 
appaiatus  (No.  9),  while  the  connection  to  the  oxygen  supply  (No.  7)  is  made 
on  the  end  of  the  first  stopcock.  To  the  first  capillary  stem  is  attached  the 
explosion  pipette  (No.  8) ;  next  in  order  is  placed  the  pipette  containing  potas- 
sium hydroxide  solution  (No.  4),  which  is  followed  by  the  burette  (No.  3). 
To  the  right  of  the  burette  are  situated  the  pipettes  containing  stick  phosphorus 
and  fuming  sulphuric  acid  (No.  6)  and  (No.  5),  respectively. 

The  stem  of  each  pipette  is  ground  so  as  just  to  clear  the  corresponding 
stem  of  the  capillary  with  which  it  is  connected.  The  stem  of  the  burette 
must  not  be  altered,  but  is  to  be  precisely  adjusted  to  the  stem  of  the  capillary 
tube  by  regulating  the  height  of  the  support  at  the  bottom.  The  numerations 
are  from  the  top  downward,  and  since  the  majority  of  readings  are  made  in  the 
lower  part  of  the  burette,  the  first  20  c  c.  are  graduated  in  fifths,  but  by  inter- 
polation, tenths  may  be  read;  the  remaining  80  c  c.  are  graduated  in  tenths, 
but  may  be  read  in  twentieths.  The  burette  is  surrounded  by  a  water  jacket, 
thereby  maintaining  practically  a  constant  internal  temperature  throughout 
the  analysis,  provided  care  is  taken  that  the  apparatus  be  not  subject  to  great 
and  sudden  change  of  temperature. 

The  pipettes  have  two  compartments,  and  to  the  open  side  a  thin  rubber 
bulb  is  attached.  This  protects  the  reagent  from  the  atmosphere.  The 
pipettes  will  conveniently  hold  100  c  c.  of  gas  and  260  c  c.  of  the  reagent,  with 
the  exception  of  the  one  for  phosphorus.  This  pipette  was  designed  for  the  use 
of  stick  phosphorus,  and  when  loosely  filled  with  this  reagent,  will  hold  100  c  c. 


12  SOLUTIONS. 


of  gas  and  sufficient  water  to  form  a  seal.  Thus  the  gas  is  exposed  to  the 
maximum  surface  area  of  the  phosphorus,  facilitating  the  absorption  of 
oxygen.  In  filling  the  pipette,  the  phosphorus  is  introduced  through  an 
opening  at  the  lower  end.  The  stem  rises  into  the  base  of  the  pipette  for  a 
distance  of  about  one-fourth  inch,  thus  preventing  the  sticks  from  obstructing 
the  orifice.  The  explosion  pipette  contains  platinum  terminals  partly  covered 
with  glass  to  prevent  the  sparks  from  short  circuiting.  In  case  the  terminals 
become  coated,  thus  preventing  the  passage  of  the  spark,  they  are  cleaned  by 
allowing  the  pipette  to  stand  inverted  in  a  mixture  of  concentrated  sulphuric 
acid  and  chromic  acid.  In  the  same  manner  the  burette  should  also  be  cleaned 
occasionally. 

The  following  auxiliary  apparatus  are  used:- 

1.  A  one-half  pint  Kipp  apparatus  for  generating  hydrogen  from  C.  P. 
stick  zinc  and  dilute  hydrochloric  acid. 

2.  An  aspirator  bottle  containing  oxygen  and  nitrogen  in  predetermined 
proportion. 

3.  An  induction  coil  of  sufficient  size  to  give  a  one-eighth  inch  spark. 
The  current  required  for  this  coil  is  deiived  either  from  dry  cells,  a  storage 
battery,  or  from  a  direct  current  lighting  circuit  with  a  rheostat  connection. 


SOLUTIONS. 

1.  Potassium  Hydroxide.     The  pipette  used  for  this  reagent  is  filled  with 
260  c  c.  of  a  solution  of  approximately  1.27  specific  gravity.     The  absorbing 
power  is  in  excess  of  40  c  c.  of  carbon  dioxide  per  c  c.  of  solution.     In  place  of 
potassium  hydroxide,  a  solution  of  sodium  hydroxide  may  be  substituted. 

2.  Stick  Phosphorus,     This  reagent  is  obtainable  in  sticks  /1e  in.  in  diam- 
eter.    It  may  also  be  prepared  from  larger  sticks  by  melting  the  phosphorus 
under  water  in  a  test  tube  immersed  in  a  vessel  of  water  at  a  temperature  of 
about  50°  C.     A  glass  tube  of  the  proper  internal  diameter  is  inserted  in  the 
molten  phosphorus,  and  a  column  of  phosphorus  is  drawn  into  the  tube  by 


AUXILIARY  GASES.  13 


means  of  suction  to  the  desired  height,  when  the  tube  is  withdrawn  and  im- 
mediately dipped  into  a  beaker  of  cold  water.  The  solidified  phosphorus  is 
then  pushed  out  with  a  glass  rod  into  the  reagent  pipette,  also  filled  with  water. 
Extreme  care  must  be  taken  to  avoid  spilling  the  phosphorus  on  the  floor. 
When  in  use,  the  water  in  the  pipette  is  renewed  occasionally  to  remove  the 
oxides  of  phosphorus  in  solution.  The  need  for  this  removal  is  indicated  when 
the  fumes  in  the  pipette  are  slowly  or  incompletely  absorbed  in  one  or  two 
minutes.  The  chamber  of  the  pipette  containing  the  phosphorus  is  enclosed 
with  a  piece  of  black  paper  to  protect  it  from  the  action  of  light. 

3.  Fuming  Sulphuric  Acid.     Two  hundred  sixty  cubic  centimeters  are 
required.     The  acid  should  contain  at  least   20%  of  the   sulphur  trioxide 
in  excess.     It  will  become  discolored  owing  to  its  action   upon   the   rubber 
tubing,  but  this  does  not  appear  to  interfere  with  its  efficiency.     This  action 
tends  to  harden  the  tubing,  and  then  apparently  ceases. 

4.  Dilute  Hydrochloric  Acid.     A  mixture  of   100  c  c.  hydrochloric  acid 
and  400  c  c.  distilled  water  is  poured  into  the  Kipp  apparatus,  the  middle 
chamber  of  which  is  well  filled  with  C.  P.  stick  zinc. 

5.  Saturated  Water.     This  water  is  used  to  fill  the  burette,  the  explosion 
pipette  and  the  leveling  bottles.     It  is  obtained  by  bubbling  the  gas  through 
20%  solution  of  sodium  sulphate  slightly  acidified  with  sulphuric  acid.     Care 
should  be  taken  not  to  contaminate  this  water  with  any  of  the  reagent  solutions. 
The  addition  of  methyl  orange  to  this  solution  will  indicate  its  becoming  alka- 
line. 

AUXILIARY  GASES. 

1.  Hydrogen.     This  gas  is  generated  in  the  middle  chamber  of  the  Kipp 
apparatus  by  the  action  of  dilute  hydrochloric  acid  (1 :4)  upon  C.  P.  stick  zinc. 
The  apparatus  should  be  flushed  several  times  with  freshly  generated  hydrogen 
to  remove  all  traces  of  air,  and  the  rubber  tubing  connected  to  the  left  end  of 
the  main  capillary  tube. 

2.  Oxygen  and  Nitrogen  Mixture.     This  mixture  should  contain  from 
35%  to  45%  oxygen  and  from  55%  to  65%  nitrogen.     A  mixture  of  one-fifth 
compressed  or  tank  oxygen,  containing  between  95%  and  100%  oxygen,  and 
four-fifths  air  will  approximate  36%     in  oxygen  content.     Connections  are 


14  OXYGEN  IN  OXYGEN  AND  NITROGEN  MIXTURE. 

made  between  two  aspirator  bottles,  one  being  filled  with  water,  and  the  other 
containing  enough  water  to  form  a  seal,  and  the  rubber  tubing  connecting  the 
two  bottles  is  closed  with  a  pinchcock.  The  volume  of  water  in  the  former  above 
the  lower  outlet  is  determined  and  a  mark  made  at  that  point.  Four-fifths  of 
this  amount  is  returned  to  the  bottle,  a  mark  being  made  on  the  side  even  with 
the  water  level,  and  the  bottle  is  then  filled  with  water.  A  connection  is  made 
with  the  oxygen  supply,  the  pinchcock  between  the  two  bottles  released,  and 
the  oxygen  is  allowed  to  pass  slowly  into  the  bottle  until  the  water  reaches  the 
indicated  mark,  the  overflow  passing  into  the  second  aspirator  bottle.  At 
this  point,  the  rubber  tubing  leading  to  the  oxygen  supply  is  disconnected,  the 
second  aspirator  bottle  is  immediately  lowered,  and  the  air  drawn  into  the 
upper  bottle  until  the  water  level  is  even  with  the  outlet.  The  end  of  the 
rubber  tubing  on  the  upper  bottle  is  closed  with  a  pinchcock,  and  the  gases 
thoroughly  mixed  by  agitation.  The  bottles  are  placed  on  their  shelves,  and 
the  tubing  connected  to  the  stem  of  the  three-way  cock  at  the  left  of  the  gas 
apparatus.  If  the  oxygen  used  contains  carbon  dioxide,  it  must  be  purified 
before  use  by  passing  through  sodium  hydroxide  or  soda  lime. 

METHODS  OF  ANALYSIS. 

1.  PERCENTAGE  OF  OXYGEN  IN  OXYGEN  AND  NITROGEN 

MIXTURE. 

In  the  application  of  the  following  methods,  it  has  been  found  that  a 
mixture  of  oxygen  and  nitrogen,  in  the  proportion  given  before,  is  the  most 
practical  for  use  in  the  combustion  of  the  component  gases,  but  it  is  necessaiy  to 
know  the  exact  percentage  of  oxygen  in  this  mixture  in  order  that  the  amount 
of  oxygen  used  for  the  explosions  may  be  known.  The  object  in  introducing 
this  mixture,  instead  of  oxygen  alone:  is  that  a  larger  volume  of  the  former 
can  be  added,  and  only  a  normal  excess  of  oxygen  will  be  present  after  the 
first  explosion,  thereby  keeping  the  explosion  ratio  as  high  as  practicable  and 
reducing  the  flame  temperature,  thus  minimizing  enors  due  to  the  oxidation  of 
nitrogen.  The  explosion  ratio  is  the  proportion  ot  the  inert  to  the  total  gases 
entering  into  the  combination.  The  oxidation  of  nitrogen  cannot  be  entirely 
avoided,  since  oxides  of  nitrogen  are  foimed  in  all  explosions  in  amounts 
varying  chiefly  with  the  temperature  attained.  The  design  of  explosion 
pipette,  owing  to  its  eudometiic  shape,  is  an  aid  in  avoiding  the  combustion 
of  nitrogen  in  that  the  flame  movement  is  slower,  and  necessarily  the  pro- 


OXYGEN  IN  OXYGEN  AND  NITROGEN  MIXTURE.  15 

duction  of  heat  is  lower  than  in  the  spherical  form  of  pipette.  Experiments 
have  been  made  on  the  gases  discussed  in  this  pamphlet,  and  approximate 
quantitative  determinations  made  of  the  oxides  of  nitrogen  formed  in  the 
combustions.  It  has  been  found  that  with  this  mixture,  and  the  explosive 
ratios  as  high  as  practicable,  the  errors  due  to  oxides  of  nitrogen  are  negligible. 
The  formation  of  oxides  of  nitrogen  cannot  be  avoided  by  not  adding  nitrogen 
as  this  gas  is  contained  to  a  greater  or  less  extent  in  all  gases  herein  analyized. 

With  the  data  of  analysis  at  hand,  the  explosion  ratio  for  the  first  explo- 
sion is  found  by  dividing  the  gas  residue  after  Contraction  II  by  the  sum  of 
Contraction  I  and  Contraction  II,  and  the  ratio  for  the  second  explosion  by 
dividing  the  residue  after  Contraction  III,  by  Contraction  III.  The  most 
practical  ratios  of  inert  to  the  combining  gases  are  those  lying  between  1.5  to 
1  and  3  to  1 ;  with  producer  gas  and  by-product  gas  the  ratio  obtained  in  the 
first  explosion  should  approach  as  near  as  possible  the  latter  ratio,  since  the 
amount  of  heat  liberated  in  the  combustion  of  methane  is  relatively  great. 

Before  beginning  the  analysis,  it  is  advisable  each  day  to  agitate  the 
bottle  containing  the  oxygen  and  the  nitrogen  mixture,  and  to  flush  out  the 
connecting  rubber  tubing  by  lowering  the  leveling  bottle  (L)  drawing  in  about 
25  c.  c.  each  of  hydrogen  and  oxygen  and  nitrogen  mixture,  and  discarding 
through  the  three-way  cock  at  the  right.  The  solutions  in  the  reagent  pipettes 
are  drawn  even  with  the  main  capillary  tube,  care  being  exercised  that  there 
are  no  unfilled  spaces  in  the  capillaries  of  the  pipettes.  The  left  half  of  the 
capillary  is  filled  with  water  drawn  over  from  the  explosion  pipette,  the  level- 
ing bottle  is  raised  and  any  portion  of  the  solutions  that  may  have  been  drawn 
into  the  main  capillary  is  expelled  through  the  stem  of  the  three-way  cock  at 
the  right,  to  which  is  attached  a  piece  of  rubber  tubing  discharging  into  a 
waste  receptacle.  While  the  leveling  bottle  is  still  raised,  the  three-way  cock 
is  closed,  and  in  this  manner  the  capillary  tube  remains  filled  with  water.  The 
leveling  bottle  is  placed  at  the  base  of  the  apparatus,  and  approximately  75  c  c. 
of  hydrogen  are  aspirated.  The  left  side  of  the  capillary  is  then  filled  with  water 
from  the  explosion  pipette  and  after  the  burette  has  drained  for  one  minute, 
the  water  in  the  leveling  bottle  is  brought  level  with  that  in  the  burette  and 
a  reading  taken.  Likewise  25  c  c.  of  the  oxygen  and  nitrogen  are  added 
and  measured  after  the  capillary  has  been  filled  and  the  burette  has  drained 
one  minute.  The  leveling  bottle  is  raised  and  the  cock  leading  to  the 


16  OXYGEN  IN  OXYGEN  AND  NITROGEN  MIXTURE. 

explosion  pipette  (8)  is  opened,  when  the  gas  is  passed  over  and  back  two  or 
three  times  to  insure  a  thorough  mixture,  as  an  imperfect  mixture  may  prevent 
the  desired  explosion. 

The  electric  circuit  is  then  closed  causing  the  explosion.  The  bottle  (Y) 
which  receives  the  overflow  from  the  explosion  pipette,  and  the  location  of 
which  on  the  lower  shelf  is  never  changed,  the  gases  thereby  being  kept  under 
partial  vacuum,  is  connected  to  the  latter  by  a  piece  of  strong  rubber  tubing 
about  a  foot  long,  partly  constricted  by  a  screw  compressor  near  the  bottles. 
The  degree  of  the  constriction  is  determined  by  increasing  it  until  no  bubbles 
apt  ear  in  the  pipette  after  an  explosion.  All  the  conditions  of  this  arrange- 
ment tend  to  diminish  the  force  of  the  resultant  explosion. 

After  the  explosion,  the  gas  is  immediately  drawn  back  into  the  burette 
until  the  water  from  the  pipette  fills  the  left  half  of  the  capillary  tube.  The 
cock  in  the  pipette  is  then  closed  and,  after  an  interval  of  one  minute  to  allow 
the  gas  to  cool,  a  reading  is  made.  This,  less  the  previous  reading,  represents 
the  contraction  due  to  the  formation  and  condensation  of  water  and  is  known 
as  Contraction  I.  The  oxygen  that  enters  into  the  explosion  is  equal  to 
one-third  of  the  contraction,  since, 

2H2  +  O2  =  2H2O.     2  volumes  +  1  volume  =  liquid  (disappearing) 
Percentage  of  oxygen  in  the  mixture  = 

Oxygen  found 


Oxygen  and  Nitrogen  Mixture  added 

Example — Data 

Burette  Readings 

0.0 

Hydrogen  added 74.6      Hydrogen  added. 

Oxygen  and  Nitrogen  74.6 

Mixture  added 25.2      Mixture  added. 

.99.8 

Explosion 27.6      Contraction. 

72.2 


X  100 


9.2       ^Contraction     or      Oxygen 
found. 


BLAST  FURNACE  GAS.  17 

Calculations. 

Oxygen  found 


X  100  =  36.5%  Oxygen. 


Oxygen  and  Nitrogen  Mixture  added 

Explosion  ratio,  2.6. 

Two  or  more  determinations  are  made  which  should  agree  within  .1  or 
.2%.  The  percentage  of  oxygen  in  the  mixture  should  be  determined  once 
each  day  while  in  use,  as  it  is  subject  to  change. 

2.  BLAST  FURNACE  GAS. 

Before  the  analysis  is  started,  the  solutions  in  the  pipettes  are  brought 
flush  with  the  capillary  tube,  while  the  latter  and  burette  are  filled  with  water. 
During  all  analyses  the  capillary  to  the  left  of  the  burette  is  always  filled  with 
water  before  a  reading  is  taken.  The  petcock  on  either  end  of  the  sample 
tube  containing  the  gas  sample  (No.  2  Analytical  Apparatus)  is  filled  with 
water  and  attached  to  the  rubber  tubing  leading  from  the  shelf  bottle  (No.  1) 
which  contains  a  10%  solution  of  sodium  chloride.  The  other  end  of  the 
sample  tube  is  attached  to  the  rubber  tubing  at  the  end  of  the  main  capillary, 
and  the  sample  tube  is  placed  in  its  rack  on  the  side  of  the  apparatus.  The 
leveling  bottle  is  then  placed  on  top  of  the  apparatus,  the  pinchcock  on  the 
water  supply,  the  lower,  then  the  upper  cock  on  the  sample  tube,  and  the 
three-way  cock  on  the  capillary  tube,  are  opened;  the  water  from  the  shelf 
bottle  forces  the  gas  into  the  burette  against  its  pressure  from  the  leveling 
bottle,  which  is  lowered  it  necessary,  the  gas  being  constantly  under  pressure. 

About  25  c  c.  of  gas  are  thus  forced  into  the  burette,  and  then  expelled 
through  the  stem  of  the  three-way  cock,  by  turning  it,  all  connections  remain- 
ing as  they  are.  This  sample  is  rejected  because  it  contains  the  air  that  was 
in  the  rubber  connection  between  the  capillary  and  sample  tube.  A  second 
sample  is  forced  in  until  it  reaches  the  base  of  the  burette,  and  one  minute  is 
allowed  for  the  burette  to  drain  and  the  temperatures  to  equalize;  duiing  this 
period  the  sample  tube  may  be  disconnected  from  the  apparatus.  With  the 
leveling  bottle  on  top  of  the  apparatus,  the  tube  leading  from  it  is  pinched 
between  the  thumb  and  finger  and  the  three-way  cock  opened,  the  pressure  of 
the  gas  being  thus  released.  The  remaining  portion  is  slowly  forced  out  by 


18  BLAST  FURNACE  GAS. 

releasing  the  pressure  on  the  tube  until  the  meniscus  just  reaches  the  100.0  c  c. 
mark  in  the  burette,  then  the  three-way  cock  is  closed.  If  the  water  in  the 
leveling  bottle  is  brought  to  the  same  level  as  that  in  the  burette,  the  meniscus 
of'the  latter  should  be  exactly  at  100.0. 

Determination  of  Carbon  Dioxide.  The  leveling  bottle  is  slowly  raised 
after  the  cock  in  the  first  reagent  pipette  containing  the  solution  of  potassium 
hydroxide  has  been  turned  so  that  the  gas  will  bubble  through  the  solution. 
If  the  leveling  bottle  be  not  raised  slowly,  the  bubbles  which  first  appear  may 
be  lost  by  being  carried  into  the  other  compartment  of  the  pipette.  When 
all  but  about  5  c  c.  of  the  gas  has  passed  into  the  pipette,  the  cock  is  turned 
to  a  position  for  drawing  the  gas  back  into  the  burette,  keeping  the  leveling 
bottle  raised,  and  the  instant  the  reagent  has  been  expelled  from  the  side 
capillary  of  the  pipette  by  the  remaining  gas,  the  leveling  bottle  is  lowered, 
and  the  gas  is  drawn  back.  Thus,  the  gas  is  forced  in  and  drawn  out  of  the 
pipette  at  least  three  times,  the  reagent  finally  being  drawn  to  its  initial 
point  in  the  stem  of  the  capillary.  The  capillary  is  filled  with  water  from 
the  explosion  pipette,  the  burette  is  allowed  to  drain  for  one  minute,  and  the 
reading  taken.  The  difference  between  this  and  the  initial  reading  represents 
the  percentage  of  carbon  dioxide  in  the  gas.  To  make  certain  that  all  the 
carbon  dioxide  has  been  removed,  the  gas  should  again  be  passed  through 
the  solution  of  potassium  hydroxide  and  a  reading  taken  as  before. 

Determination  of  Oxygen.  The  passing  of  the  residue  from  the  absorp- 
tion of  carbon  dioxide  into  the  fuming  sulphuric  acid  for  the  absorption  of 
the  illuminants  or  olefiant  gases  is  usually  omitted  with  blast  furnace  gas, 
as  these  are  either  entirely  absent  or  present  only  in  such  small  quantities 
that  they  can  scarcely  be  detected  in  the  usual  way.  Therefore,  the  residue 
is  at  once  passed  into  the  second  pipette  containing  stick  phosphorus  and 
left  there  for  one  minute  to  remove  the  small  amount,  it  any,  of  oxygen 
found  in  blast  furnace  gas.  The  difference  between  the  burette  reading 
obtained  and  that  after  the  absorption  of  carbon  dioxide,  represents  the 
percentage  of  oxygen  present. 

Determination  of  Carbon  Monoxide,  Hydrogen  and  Methane.  One-half  the 
above  residue  is  used  for  the  determination  of  these  gases;  if  it  is  desired  to 
duplicate  the  explosion,  one-half  of  the  residue  is  reserved  in  the  phosphorus 
pipette.  If  not,  the  leveling  bottle  is  placed  on  top  of  the  apparatus,  the 


BLAST  FURNACE  GAS.  19 

connecting  rubber  tubing  pinched,  and  the  residue  to  be  rejected  is  slowly 
forced  out  through  the  stem  of  the  three-way  cock  until  the  meniscus  just 
reaches  the  calculated  point.  The  three-way  cock  is  closed  and  by  the 
application  of  the  leveling  bottle  the  calculated  reading  should  be  obtained. 

A  volume  of  oxygen  and  nitrogen  mixture  containing  about  16  c  c. 
oxygen  is  now  passed  into  the  burette  through  the  permanent  rubber  tubing 
connection,  and,  the  capillary  being  filled  with  water,  an  exact  reading  is  made. 
If  the  carbon  dioxide,  in  the  absence  of  oxygen,  is  low  in  the  sample,  it  indicates 
a  gas  rich  in  combustibles,  in  which  case  a  proportional  increase  is  made  in 
the  amount  of  the  oxygen  and  nitrogen  mixture  added.  The  leveling  bottle 
is  raised,  the  cock  leading  to  the  explosion  pipette  opened,  and  the  gases 
are  passed  over  and  back  two  or  more  times  to  insure  a  thorough  mixture; 
the  gases  are  then  exploded,  drawn  back  into  the  burette  and,  after  one 
minute,  Contraction  I  is  noted. 

The  residual  gas  is  passed  through  the  potassium  hydroxide  pipette 
at  least  three  times  to  remove  all  the  carbon  dioxide.  After  the  burette  has 
drained,  a  reading  is  made,  which,  less  the  preceding  reading,  gives  Contraction 
II.  The  residual  gas  consists  of  nitrogen  and  oxygen,  and,  for  the  purpose 
of  calculation,  the  oxygen  must  be  known.  About  25  c  c.  of  hydrogen  are 
added,  an  exact  reading  is  taken,  and  the  gases  are  passed  back  and  forth 
into  the  explosion  pipette  until  thoroughly  mixed.  The  gases  are  exploded, 
drawn  back  into  the  burette,  allowed  to  drain  and  cool,  and  a  reading  is  noted. 
This  reading,  less  the  former,  represents  the  contraction  due  to  the  combus- 
tion of  hydrogen  and  oxygen.  This  result  is  known  as  Contraction  III, 
and  one-third  of  it  represents  the  oxygen  present  prior  to  the  last  explosion. 

In  the  analysis  of  all  gases  there  should  be  an  excess  of  hydrogen  after 
Contraction  III,  hence  two-thirds  of  Contraccion  III  should  be  less  than  the 
hydrogen  added;  if  it  is  not  less,  oxygen  still  remains,  which  is  removed  by 
passing  the  residue  into  the  phosphorus  pipette.  The  contraction  is  noted, 
multiplied  by  three  and  added  to  Contraction  III;  one-third  of  this  total  is 
the  oxygen  present  prior  to  the  last  explosion. 

The  remaining  gas  consists  of  nitrogen  and  hydrogen,  which  do  not 
enter  into  the  subsequent  calculations,  as  all  the  necessary  data  have  been 
obtained  for  calculating  the  amounts  of  carbon  monoxide,  hydrogen,  methane 
and  nitrogen  that  existed  in  the  original  mixture.  The  reactions  which  take 


20  BLAST  FURNACE  GAS. 

place  in  the  combustions  are  as  follows:  2CO  +  O2  =  2CO2,  or  two  volumes 
of  carbon  monoxide  unite  with  one  volume  of  oxygen  forming  two  volumes 
of  carbon  dioxide,  there  being  a  contraction  of  one  volume.  Therefore,  the 
contraction  and  the  oxygen  used  are  each  one-half  the  carbon  monoxide,  and 
the  carbon  dioxide  formed  has  the  same  volume  as  the  monoxide. 
2H2  +  O2  =  2H2O,  or  two  volumes  of  hydrogen  unite  with  one  volume  of 
oxygen  forming  water  vapor  which  condenses,  the  contraction  being  three 
volumes.  The  contraction  is  then  three-halves  the  hydrogen,  and  the  oxygen 
consumed  is  one-half  the  hydrogen.  CH4  +  2O2  =  CO2  +  2H2O,  or  one 
volume  of  methane  unites  with  two  volumes  of  oxygen  forming  one  volume 
of  carbon  dioxide,  the  water  condensing  and  the  contraction  being  two  vol- 
umes. The  contraction  and  the  oxygen  used  are  each  twice  the  methane 
and  the  carbon  dioxide  has  the  same  volume  as  the  methane. 

From  these  facts  the  following  equations  are  formed: 
Contraction  I  =  %  Carbon  Monoxide  +  %  Hydrogen  +  2  Methane. 
Contraction  II  =  Carbon  Monoxide  +  Methane. 

Oxygen  consumed  =  %  Carbon  Monoxide  +  ^  Hydrogen  +  2  Methane. 
Also,  Oxygen  consumed  =  Oxygen  added —  1A  Contraction  III. 
From  these  equations,  several  formulae  may  be  derived  for  calculating 
the  components  of  the  original  mixture.     The  simplest  are: 

Hydrogen  =  Contraction  I  +  Y*  Contraction  III  —  Oxygen  added. 

Con.  I  +  (4  X  Con.  II)  +Con.  III. 

Carbon  Monoxide  = Oxygen  added. 

3 

Methane  =  Contraction  II  —  Carbon  Monoxide  present. 

As  the  analysis  by  explosion  was  performed  on  half  portion,  the  results 
must  be  doubled  for  expression  of  percentage.  Nitrogen  is  obtained  by 
difference,  i.  e.,  it  is  equal  to  100  minus  the  sum  of  the  percentages  of  the 
other  constituents  of  the  gas. 

Example — Data. 

Burette  Readings. 
100.0 

Potassium  Hydroxide 13.0     Carbon  Dioxide. 

87.0 

Stick  Phosphorus 0.0     Oxygen. 

87.0         Residue. 


BLAST  FURNACE  GAS. 


21 


Burette 

Readings. 

43.5 

1/2     Residue. 

Oxygen  and  Nitrogen 

44.1     Mixture  added, 

Mixture  added 

36.5%     Oxygen. 

87.6 

16.1     Oxygen  added. 

Explosion  

9.3     Contraction  I. 

78.3 

Potassium  Hydioxide 

12.9     Contraction  II. 

65.4 

Hydrogen  added  ...... 

27.5     Hydrogen  added. 

92.9 

Explosion 

, 

26.1     Contraction  III. 

66.8 

8.7     1A  Contraction  III,  or  Oxyge 

n  exces?. 


Calculations: 

9.3     Contraction  I. 

8.7       %  Contraction  III. 


18.0 

16.1     Oxygen  added. 


1.9  Hydrogen  present. 

9.3  Contraction  I. 

51.6  4  X  Contraction  II. 

26.1  Contraction  III. 


Analysis. 


Carbon  Dioxide 13.0% 

Oxygen 0.0% 

Carbon  Monoxide 25.8% 

Methane 0.0% 

Hydrogen 3.8% 

Nitrogen 57.4% 


87.0  Total. 

29.0  K  Total. 

16.1  Oxygen  added. 

12.9  Carbon  Monoxide  present. 

12.9  Contraction  II. 

.0  Methane  present. 
Explosion  ratios:— I,  3.1;  II,  2.6 


100.0% 


22  PRODUCER  GAS. 


Occasionally  it  is  found  that  the  gas  when  mixed  with  hydrogen  for  the 
second  explosion  will  not  explode,  due  to  the  fact  that,  the  gas  sample  being 
abnormally  high  in  combustibles,  an  insufficient  amount  of  oxygen  remains 
after  the  first  explosion.  In  such  case  the  gas  is  drawn  back  into  the  burette 
and  the  oxygen  and  nitrogen  mixture  is  added  until  the  volume  approaches 
100  c  c.;  the  gases  are  again  mixed,  exploded  and  the  analysis  completed  as 
usual,  the  oxygen  added  being  tound  from  the  sum  of  the  two  additions. 
If,  in  the  first  explosion  of  any  analysis,  the  explosion  ratio  of  inert  to  com- 
bining gases  is  not  sufficiently  high,  and  doubt  exists  as  to  the  formation  ot 
oxides  of  nitrogen,  the  explosion  and  resulting  determinations  may  be  dupli- 
cated, using  a  larger  amount  of  oxygen  and  nitrogen  mixture  and  the  portion 
of  the  residue  which  has  been  reserved  in  the  phosphorus  pipette,  or  the 
residue  from  a  new  portion  may  be  obtained  in  the  following  manner:  One 
hundred  cubic  centimeters  are  taken  from  the  original  sample  and  the  carbon 
dioxide,  oxygen,  and  illuminants  if  present,  are  removed  in  the  usual  manner. 
The  residue  may  not  be  the  same  as  that  obtained  on  the  first  sample  on 
account  of  the  reduction  in  volume  of  the  carbon  dioxide,  due  to  its  slight 
solubility  in  the  solution  in  the  sample  tube,  but  a  part  of  the  residue  is 
taken  equal  in  volume  to  the  gas  used  in  the  first  explosion,  and  the  analysis 
is  continued  as  usual.  When  the  apparatus  is  not  in  use,  the  leveling  bottle 
is  raised  and  the  residue  from  the  previous  analysis  is  forced  into  each  of  the 
pipettes  so  as  to  clear  the  stop-cocks;  this  is  done  to  prevent  the  stop-cocks 
from  sticking. 

3.     PRODUCER  GAS. 

For  the  analysis  of  producer  gas  the  method  as  described  under  Blast 
Furnace  Gas  is  used  with  one  or  two  modifications  as  subsequently  described. 

Determinations  of  Carbon  Dioxide  and  Illuminants.  A  sample  of  exactly 
100  c.  c.  is  measured  and  the  carbon  dioxide  removed.  Next,  the  gas  is 
bubbled  twice  through  the  fuming  sulphuric  acid  pipette  to  absorb  the  un- 
saturated  hydrocarbons,  composed  chiefly  of  ethylene  and  commonly  called 
illuminants.  Care  must  be  exercised  not  to  allow  any  water  to  enter  the 
pipette.  After  the  acid  has  been  drawn  to  its  initial  point  in  the  stem  of  the 
pipette,  the  gas  is  passed  into  the  solution  of  potassium  hydroxide  two  or 
three  times  to  remove  the  white  acid  fumes,  and  a  reading  is  taken.  The 
decrease  in  volume  indicates  the  percentage  of  illuminants  present. 


PRODUCER  GAS.  23 


Determination  of  Oxygen.  The  gas  is  passed  into  the  pipette  containing 
stick  phosphorus  and  left  there  while  the  oxygen  and  nitrogen  mixture  required 
for  the  combustion  described  below  is  introduced  into  the  burette,  measured, 
and  transferred  to  the  explosion  pipette.  The  gas  residue  in  the  stick  phos- 
phorus pipette  is  then  returned  to  the  burette  and  measured;  the  diminution 
in  volume  is  oxygen. 

Determination  of  Carbon  Monoxide,  Hydrogen  and  Methane.  The  amount 
of  oxygen,  necessary  for  the  combustion  of  the  residue  from  producer  gas  is 
more  than  that  for  blast  furnace  gas,  since  the  percentage  of  combustibles  is 
greater.  The  oxygen  used  in  the  explosion  with  one-half  the  residue  from 
100  c  c.  of  gas  varies  between  8  and  12  c  c.  and  at  least  8  or  12  c  c.  should 
remain  for  the  second  explosion;  therefore,  20  c  c.  oxygen  (in  the  oxygen 
nitrogen  mixture)  are  sufficient  for  both  explosions.  If  this  20  c  c.  oxygen 
were  added  pure,  the  first  explosion  would  be  violent,  endangering  the  pipette 
and  causing  the  formation  of  oxide  of  nitrogen.  If  more  oxygen  were  added, 
the  addition  of  more  hydrogen  than  described  here  would  have  to  be  made, 
arid  the  resultant  explosion  would  be  violent. 

A  volume  of  the  oxygen  and  nitrogen  mixture  containing  about  20  c  c. 
oxygen  is  drawn  into  the  burette  from  the  overhead  bottle,  while  the  gas 
residue  is  in  the  stick  phosphorus  pipette  as  described  above.  The  capillary 
is  filled  with  water  from  the  explosion  pipette,  a  reading  is  taken,  and  the 
gas  is  passed  into  the  explosion  pipette.  The  gas  in  the  stick  phosphorus 
pipette  is  transferred  to  the  burette,  and  the  oxygen  determined;  one-half 
is  passed  into  the  phosphorus  pipette  or  discarded,  and  the  other  half  is 
passed  into  the  explosion  pipette.  The  gases  are  mixed  and  then  exploded; 
the  gases  are  returned  to  the  burette  and  allowed  to  cool,  and  treading  is 
taken.  Contraction  I  is  found  by  subtracting  the  gas  volume  remaining 
after  the  explosion  from  the  sum  of  the  residue  taken  for  the  explosion  and 
the  auxiliary  gas  added.  Contraction  II,  the  carbon  dioxide  formed  during 
the  explosion,  is  determined  by  the  gases  being  passed  through  the  potassium 
hydroxide  solution.  For  the  combustion  of  the  remaining  oxygen,  hydrogen 
is  added.  Since  20  c  c.  oxygen  were  added,  and  at  least  8  c  c.  were  consumed 
in  the  explosion,  the  amount  remaining  is  less  than  12  c  c.,  and  25  c  c.  hydrogen 
are  sufficient.  The  reading  after  Contraction  II  is  generally  less  than  75, 
and  hydrogen  is  added  to  the  capacity  of  the  burette,  when  the  gases  are 


24 


PRODUCER  GAS. 


passed  into  the  explosion  pipette.  If  the  reading  after  Contraction  II  be 
more  than  75,  the  gas  is  passed  into  the  potassium  hydroxide  pipette  and 
25-30  c  c.  hydrogen  drawn  in  and  measured  (the  capillary,  as  always,  being 
filled  with  water).  The  hydrogen  is  then  passed  into  the  explosion  pipette, 
and  the  gas  in  the  alkaline  pipette  drawn  into  the  burette  and  forced  into 
the  explosion  pipette.  The  gases  are  mixed,  exploded,  drawn  back  into  the 
burette,  allowed  to  cool,  and  a  reading  is  taken.  The  reduction  in  volume  is 
designated  Contraction  III. 


Example — Data. 

Burette  Readings. 
100.0 

Potassium  Hydroxide 4.5      Carbon  Dioxide. 

95.5 

Fuming  Sulphuric  Acid .5      Illuminants. 

95.0 

Stick  Phosphorus .0      Oxygen. 

95.0         Residue. 


Oxygen  and  Nitrogen  Mixture 
added  while  gas  in  Phos- 
phorus Pipette. 


47.5         Y2  Residue. 


55.0     Mixtureadded,36.5%Oxygen. 
55.0  (20.1  Oxygen  added.) 

47.5 


Explosion. 


Potassium  Hydroxide. 

Hydrogen  added 

Explosion 


95.8 


72.7 


102.5      Volume 

83.8 


83.8         18.7      Contraction  I. 
14.3      Contraction  II. 
69.5 


23.1       Contraction  III. 


BY-PRODUCT  GAS. 


25 


Calculations: 

18.7      Contraction  I. 
7.7       14  Contraction  III. 


26.4 

20.1   Oxygen  added. 

6.3   Hydrogen  present.- 


18.7  Contraction  I. 

57.2  4  X  Contraction  II. 

23.1  Contraction  III. 

99.0  Total. 

33.0  \i  Total. 

20.1  Oxygen  added. 


Analysis. 


Carbon  Dioxide 

Illuminants 

Oxygen 

Carbon  Monoxide.  . . 

Methane 

Hydrogen 

Nitrogen 


.  4.5% 

.  0.5% 

.  0.0% 

,  25.8% 

,  2.8% 

,  12.6% 

.  53.8% 

100.0% 


12.9      Carbon  monoxide  present. 
14.3      Contraction  II. 

1.4      Methane  present. 
Explosion  Ratios:— I,  2.1;  II.  3.1. 


4.     BY-PRODUCT  GAS. 


Determination  of  Carbon  Dioxide.  One  hundred  cubic  centimeters  of 
the  gas  are  measured,  and  the  carbon  dioxide  is  absorbed  in  the  potassium 
hydroxide  pipette. 

Determination  of  Illuminants.  The  residue  after  carbon  dioxide  has 
been  removed  is  passed  through  the  fuming  sulphuric  acid  pipette  two  or 
three  times,  care  being  taken  to  keep  water  out  of  the  pipette.  After  the 
gas  has  been  drawn  to  its  initial  point  in  the  stem  of  the  pipette,  the  fumes 
of  sulphur  trioxide  are  removed  by  being  passed  through  the  potassium 
hydroxide  pipette.  The  contraction  in  volume  is  noted  as  illuminants  and 


26  BY-PRODUCT  GAS. 


consists  of  ethylene,  C2H4,  and  its  homologues  and  also  benzene,  CQH6. 
The  latter  may  vary  from  1%  in  the  raw  gas  to  .2%  in  the  debenzolized 
gas.  It  may  be  determined  and  deducted  as  described  subsequently. 

Determination  of  Oxygen.  The  gas,  after  the  removal  of  illuminants. 
is  passed  into  the  phosphorus  pipette  for  the  absorption  of  oxygen.  While 
here  the  oxygen  and  nitrogen  mixture  necessary  for  the  combustion  of  the 
residue  as  subsequently  described  is  drawn  into  the  burette,  measured,  and 
passed  into  the  explosion  pipette.  The  gas  in  the  phosphorus  pipette  is 
drawn  back  into  the  burette  and  measured;  the  diminution  in  volume  is  oxygen. 

Analysis  of  the  Residue.  The  gas  after  the  removal  of  the  above  absorb- 
able  constituents  consists  of  carbon  monoxide,  hydrogen,  and  members  of 
the  paraffine  group,  CnH2n+2,  chiefly  methane,  CH4,  but  also  some  ethane, 
C2H6.  The  determinations  of  ethane  would  necessitate  the  removal 
of  carbon  monoxide  and  hydrogen  before  explosion  as  only  two  members 
of  the  paraffine  group  (hydrogen  being  considered  the  first  member)  can 
be  determined  by  explosion.  However,  by  the  combustion  of  the  residue 
of  carbon  monoxide,  hydrogen,  methane  and  ethane  and  calculation  of  the 
results,  by  the  formulae  given  under  blast  furnace  gas,  to  carbon  monoxide, 
hydrogen  and  methane,  no  appreciable  error  is  introduced.  The  carbon 
monoxide  obtained  is  the  same  no  matter  what  paraffines  are  present.  Ethane 
is  not  determined  separately,  but  is  burned  with  the  methane,  so  that  the 
actual  percentage  of  methane  is  increased  and  the  actual  percentage  of 
hydrogen  is  decreased,  that  is,  H2  +  CH4  (by  analysis)  =  H2  +  CH4  + 
C2H6  (actual).  Therefore,  the  sum  of  the  combustibles  and  consequently 
the  nitrogen  remain  true  values. 

\ 
Example: 

Gas  Contains  Analysis  obtained  by  explosion. 

13.3%  CO  13.3% 

31.0%  CH4  34.6% 

37.6%  H2  35.8% 

1.8%  C2H6 

4.7%  N2  4.7% 


88.4%  88.4% 


BY-PRODUCT  GAS.  27 


The  thermal  values  are  nearly  the  same,  being,  for  the  lesidue  exploded, 
456.8  B.  t.  u.  Actual. 
455.4  B.  t.  u.  By  Analysis. 

1.4  B.  t.  u.  Error  of  .3%  of  the  total  heat  value. 

The  amount  of  air  necessary  for  combustion  and  the  products  of  com- 
bustion as  calculated  from  this  analysis  are  correct,  since  the  analysis  is 
obtained  by  measurement  of  the  oxygen  used  and  the  products  of  combustion 
formed. 

The  residue  from  absorption  of  by-product  gas  is  very  high  in  com- 
bustibles and  consequently  one-fourth  is  used  for  explosion.  The  oxygen 
required  for  the  combustion  of  one-quarter  of  the  residue  from  100  c  c.  of 
gas  is  from  20  to  25  c  c.  and  there  should  be  an  excess  of  from  8  to  12  c  c.  to 
make  proper  explosion  with  the  hydrogen  subsequently  added,  a  total  of 
33  c  c.  being  required.  That  the  proper  explosion  ratios  be  obtained,  the 
oxygen  is  diluted  with  nitrogen  as  is  done  in  the  case  of  blast  furnace  and 
producer  gas. 

While  the  residue  from  100  c  c.  of  the  gas  is  in  the  phosphorus  pipette, 
as  mentioned  under  determination  of  oxygen,  a  volume  of  oxygen  and  nitrogen 
mixture  containing  about  33  c  c.  oxygen  is  drawn  into  the  burette,  measured, 
the  capillary  being  filled  with  water,  and  transferred  to  the  explosion  pipette. 
The  gas  in  the  phosphorus  pipette  is  then  brought  back  into  the  burette, 
measured,  and  all  but  exactly  one-quarter  discarded  or  forced  into  the  phos- 
phorus pipette. 

If  the  entire  quarter  of  the  residue  were  passed  into  the  explosion  pipette, 
and  the  gases  exploded  after  being  mixed,  the  explosion  ratio  would  be  too 
low:  1.6  if  35%  oxygen-nitrogen  mixture  were  added  and  1.0  if  45%  mixture 
were  used.  To  avoid  this,  10  c  c.  of  the  gas  are  passed  into  the  explosion 
pipette  and  exploded.  The  remaining  gas  is  passed,  the  gases  well  mixed, 
and  another  explosion  made.  The  ratio  of  the  first  explosion  as  calculated 
is  very  high,  but  it  is  probable  that,  the  gases  not  being  well  mixed  and  the 
more  combustible  ones  lying  on  the  top,  the  actual  ratio  is  lower.  The 
second  ratio  is  approximately  3.  The  gas  is  passed  into  the  burette  and 
measured  alter  one  minute  lor  cooling  and  draining.  Contraction  I  is  cal- 
culated. The  gas  is  then  passed  into  the  potassium  hydroxide  pipette  for 


28 


BY-PRODUCT  GAS. 


the  absorption  of  carbon  dioxide;  the  diminution  in  volume  is  Contraction  II. 
The  residue  is  next  passed  into  the  potassium  hydroxide  pipette,  and  hydrogen 
sufficient  to  make  a  total  volume  of  about  115  c  c.  is  drawn  into  the  burette 
and  measured,  the  capillary  being  filled  with  water.  The  hydrogen  is  passed 
into  the  explosion  pipette,  and  the  gas  in  the  potassium  hydroxide  pipette 
is  drawn  back  into  the  burette  and  forced  into  the  explosion  pipette.  The 
gases  are  mixed  and  exploded,  then  drawn  back  into  the  burette  and  measured. 
The  difference  in  volume  is  designated  Contraction  III. 

The  volumes  of  oxygen  and  hydrogen  given  in  the  preceding  paragraph 
will  apply  to  all  by-product  gases  generally  analyzed.  If  gases  rich  in  com- 
bustibles be  encountered,  the  oxygen  should  be  increased,  likewise  with  a 
lean  gas,  the  oxygen  may  be  reduced. 

Example — Data. 


Burette  Readings. 

100.0 

Potassium  Hydroxide  

1.8 

Carbon  Dioxide. 

98.2 

Fuming  Sulphuric  

2.4 

Illuminants. 

95.8 

Stick  Phosphorus  

.2 

Oxygen. 

95.6 

23.9 

H 

Residue. 

0.0 

Oxygen  and  Nitrogen  Mixture 

91.0 

Mixture,  36.5%  Oxygen. 

91.0 

33.22  c  c.  Oxygen. 

Explosion                       

23.9 

81.0 

114.9 

Potassium  Hydroxide  

73.1 

81.0 

Contraction    I. 

33.9 

7.9 

Contraction  II. 

Hydrogen  added 

73.1 

40.0 

40.0 

113.1 

Explosion                      

75.3 

75.3 

Contraction  III. 

37.8 

FLUE  GAS. 


29 


Calculations: 


33.9     Contraction  I. 
12.6     \4  Contraction  III. 


Analysis. 


46.5 

33.22     Oxygen  added. 


13.28  Hydrogen  present. 

33.9  Contraction  I. 

31.6  4  X  Contraction  II. 

37.8  Contraction  III. 
103.3 


34.43 

33.22     Oxygen  added. 


1.21     Carbon  Monoxide. 
7.9       Contraction  II. 


6.69     Methane. 


Carbon  Dioxide 1.8% 

Illuminants 2.4% 

Oxygen 2% 

Carbon  Monoxide 4.8% 

Methane 26.8% 

Hydrogen 53.1% 

Nitrogen 10.9% 

100.0% 


5.     FLUE  GAS. 


The  repeated  determination  of  large  quantities  of  oxygen  by  stick  phos- 
phorus or  pyrogallol  solution  introduces  undesirable  features  with  the  use 
of  either  reagent.  In  the  former  case,  unless  care  is  exercised,  the  heat  of 
reaction  causes  fusion  with  consequent  disarrangment  of  the  phosphorus 
sticks;  with  the  use  of  the  latter  reagent  there  is  a  possibility  of  the  incomplete 
absorption  of  all  the  oxygen.  In  such  a  case  it  would  be  absorbed  in  the 
cuprous  chloride  solution  with  the  carbon  monoxide,  if  this  were  used  for 
the  purpose,  thus  giving  erroneous  values  to  the  carbon  monoxide  found. 
To  overcome  these  difficulties  the  following  method  has  been  devised  whereby 
the  oxygen  and  carbon  monoxide  are  determined  by  explosion;  it  has 
proven  superior  to  the  absorption  method,  which  is  usually  followed  in  the 
analysis  of  flue  gases. 


30  FLUE  GAS. 


Determination  of  Carbon  Dioxide.  This  constituent  is  determined  on 
exactly  100  c  c.  measured  in  the  usual  way,  as  described  under  Blast  Furnace 
Gas. 

Determination  of  Oxygen  and  Carbon  Monoxide.  One-half  of  the  volume 
of  the  residual  gases  is  rejected.  To  the  remaining  half,  hydrogen  is  added 
to  combine  with  the  oxygen.  More  oxygen  must  be  added  to  insure  sufficient 
for  the  first  and  second  explosions.  A  total  of  18  c  c.  oxygen  should  be 
present.  The  oxygen  in  the  residual  gas  varies  inversely  with  the  carbon 
dioxide  and  also  according  to  the  source  from  which  the  flue  gas  was  derived. 
The  following  table  shows  approximately  the  amount  of  oxygen  present  in 
50  c  c.  of  gas  and  the  amount  to  be  added  in  the  form  of  the  oxygen  and 
nitrogen  mixture.  ("CO2"  is  percent,  found.) 

Source  of  Flue  Gas  O2  present  in  50  c.  c.        O2  to  be  added 

Coal  and  Producer  Gas  10  c  c.  —  .5  CO2  8  c  c.  +  .5  CO2 

Blast  Furnace  Gas  10  c  c.  —  .4  CO2  8  c  c.  +  .4  CO2 

By-Product  Gas  10  c  c.  —  CO2  8  c  c.  +  CO2 

Natural  Gas  10  c  c.  —  .8  CO2  8  c  c.  +  .8  CO2 

The  method  of  procedure  is  as  follows:  To  one-half  the  residue,  16  c  c. 
of  hydrogen  are  added,  the  capillary  is  filled  with  water,  and  a  reading  is  taken. 
The  oxygen  and  nitrogen  mixture  containing  the  calculated  amount  of  oxygen 
is  then  added,  and  a  reading  is  taken.  The  gases  are  passed  into  the  explosion 
pipette,  well  mixed  and  exploded.  The  residue  is  drawn  into  the  burette  and 
measured,  the  decrease  in  volume  is  Contraction  I.  Contraction  II  is  found 
by  passing  the  gas  through  the  potassium  hydroxide  pipette.  Hydrogen 
is  added  to  the  capacity  of  the  burette  (at  least  26  c  c.  must  be  added). 
A  reading  is  taken,  and  the  gases  are  transferred  to  the  explosion  pipette, 
mixed  and  exploded.  The  residue  is  returned  to  the  burette  and  measured; 
Contraction  III  is  thus  obtained. 

The  data  necessary  for  the  calculation  of  the  percentage  of  oxygen  and 
carbon  monoxide  in  the  sample  have  thus  been  obtained.  From  the  reactions 
given  under  the  determination  of  carbon  monoxide,  hydrogen  and  methane 
in  blast  furnace  gas,  it  is  seen  that  when  one  volume  of  oxygen  unites  with 
two  volumes  of  carbon  monoxide,  there  is  a  contraction  of  one  volume  and  the 
formation  of  two  volumes  of  carbon  dioxide,  which  on  absorption  causes  a 


FLUE  GAS.  31 


further  contraction  of  two  volumes;  the  total  contraction  is,  therefore,  three 
volumes  for  one  volume  oxygen,  or  the  oxygen  is  one-third  the  total  contrac- 
tion. The  carbon  monoxide  was  also  shown  to  have  the  same  volume  as  the 
dioxide  formed.  In  the  combustion  of  hydrogen  and  oxygen,  it  was  shown 
that  the  oxygen  is  one-third  the  contraction.  Then  the  oxygen  entering 
the  two  explosions,  or  the  total  oxygen,  is  one-third  the  sum  of  the  three 
contractions,  and  the  oxygen  in  the  sample  is  found  by  subtracting  the 
oxygen  added  from  this  total  oxygen.  These  facts  are  expressed  in  the 
following  equations: 

Carbon  Monoxide  =  Contraction  II. 

Con.  I  +  Con.  II  +  Con.  Ill 

Oxygen  in  sample  = •  — Oxygen  added. 

3 

The  absence  of  methane  and  hydrogen  in  a  flue  gas  may  be  proven  by 
the  application  of  this  formula: 

H2  -f  CH4  = — •  —  H2  added  for  the  first  explosion. 


Example —  Data. 

Burette  Readings. 

100.0 
Potassium  Hydroxide 10.0%  Carbon  Dioxide. 

90.0 

45.0          ]4  Residue. 
Hydrogen  added 16.2  c  c.  Hydrogen. 

61.2 
Oxygen  and  Nitrogen  Mixture  35.8 — 13.07  c  c.  Oxygen  added. 

97.0 
Explosion 24.7     Contraction      I. 

72.3 
Potassium  Hydroxide .8     Contraction    II. 

71.5 
Hydrogen  added 

99.5 
Explosion 2d.O     Contraction  III. 

73.5 


32  NATURAL  GAS. 


Calculations. 


.8  Contraction  II  or  Carbon  Monoxide. 

24.7  Contraction  I.  Analysis. 

.8  Contraction  II.  Carbon  Dioxide 10.0% 

26.0  Contraction  III.  Oxygen 8.2% 

Carbon  Monoxide 1-6% 

17.17  Nitrogen 80.2% 

13.07 


4.10     Oxygen  present.  100.0% 

Explosion  Ratios:— 2.8  —  2.8. 

0.     NATURAL  GAS. 

The  analysis  of  natural  gas  by  the  methods  given  for  the  other  fuel 
gases  described  herein  is  not  very  satisfactory.  If  but  little,  say  10  c  c.,  of 
the  methane  and  ethane  are  exploded  with  oxygen,  any  error  in  reading  is 
multiplied  many  times.  Again  on  combustion  of  a  large  quantity  with 
oxygen,  the  resultant  gas  is  nearly  pure  carbon  dioxide  and,  its  solubility  in 
water  varying  with  its  percentage,  consequently  a  relatively  large  quantity 
is  dissolved.  The  second  contraction,  i.  e.,  on  absorption  of  carbon  dioxide, 
being  low,  the  result  is  that  the  sum  of  the  methane  and  ethane  obtained 
by  calculation  is  over  100,  and  the  nitrogen  a  minus  quantity.  To  overcome 
these  defects,  use  is  made  of  the  following  method  in  which  the  contraction 
on  explosion  and  on  absorption  of  the  carbon  dioxide  is  treated  as  one  known 
factor  and  the  oxygen  entering  into  combination  the  other  factor. 

Percentage  of  Oxygen  in  Commercial  Oxygen.  Commercially  pure  oxygen 
is  used  instead  of  the  oxygen  and  nitrogen  mixture  of  previous  methods. 
This  practice  is  necessary  on  account  of  the  great  amount  of  oxygen  required 
for  combustion.  The  determination  of  the  percentage  of  oxygen  is  made  by 
exploding  a  large  quantity  of  it  with  hydrogen  and  noting  the  resultant 
contraction,  of  which  one-third  equals  the  oxygen.  The  determination  is  best 
accomplished  in  the  following  manner:  about  100  c  c.  of  pure  hydrogen  are 
forced  into  the  burette,  the  capillary  is  filled  with  water  from  the  explosion 
pipette,  a  reading  is  taken,  and  the  gas  is  forced  into  the  explosion  pipette 
until  the  water  level  is  at  zero;  about  100  c  c.  more  hydrogen  are  introduced, 
and  a  reading  is  taken,  the  gas  is  then  forced  into  the  explosion  pipette 


NATURAL  GAS.  33 


until  the  water  level  is  again  at  zero.  About  60-65  c  c.  oxygen  are  then  added, 
a  reading  is  taken,  and  15  c  c.  portions  are  successively  introduced  into  the 
explosion  pipette  and  exploded,  the  gases  being  well  mixed  before  the  last 
explosion.  After  the  final  explosion,  the  residue  is  drawn  over,  the  capillary 
being  filled  with  water,  and  a  reading  is  taken.  One-third  of  the  contraction 
is  oxygen,  from  which  the  percentage  can  be  calculated. 

Determination  of  Carbon  Dioxide.  Exactly  100  c  c.  are  forced  into  the 
burette  from  the  sampling  tube,  as  described  previously.  A  reading  is 
taken,  and  the  gas  is  passed  through  the  potassium  hydroxide  pipette  for  the 
absorption  of  carbon  dioxide,  then  returned  to  the  burette,  and  the  capillary 
filled  with  water  from  the  explosion  pipette.  A  reading  is  taken;  the  con- 
traction in  volume  is  the  percentage  of  carbon  dioxide. 

Determination  of  Jlluminants.  The  use  of  fuming  sulphuric  acid  is  not 
advisable  here  as  it  absorbs  the  higher  members  of  the  paraffine  group.  In 
its  place  is  substituted  a  pipette  containing  a  1%  solution  of  palladium 
chloride.  The  gas  is  passed  three  times  through  this  solution  and  returned 
to  the  burette,  the  contraction  being  illuminants,  ethylene  and  its  homologues. 
The  contraction  in  volume  would  also  include  hydrogen  and  carbon  monoxide, 
if  present;  however,  the  rate  of  absorption  of  these  gases  is  comparatively 
slow.  They  are  generally  absent,  and  their  absence  is  proved  by  the  method 
described  later.  One  passage  of  natural  gas  through  fuming  sulphuric  acid 
gives  about  the  same  contraction  as  the  method  described  herein,  but  repeated 
passages  take  out  more  and  more  of  the  paraffines.  No  definite  result  is 
obtained. 

Determination  of  Oxygen.  After  absorption  of  illuminants,  the  gas  is 
passed  into  the  phosphorus  pipette  for  the  absorption  of  oxygen,  and  while 
it  is  there,  the  requisite  amount  of  oxygen  is  measured  in  the  burette  and 
transferred  to  the  explosion  pipette.  The  gas  in  the  phosphorus  pipette  is 
then  returned  to  the  burette,  and  the  contraction  due  to  absorption  of  oxygen 
is  noted. 

Determination  of  Methane  and  Ethane.  The  gas  residue  consists,  besides 
the  small  quantity  of  nitrogen,  of  methane,  ethane  and  perhaps  other  higher 
homologues.  It  is  impossible  by  any  method  to  determine  more  than  two 
gases  of  the  paraffine  group  by  combustion,  and  the  gases  are  assumed  to 
consist  of  methane  and  ethane.  No  error  is  introduced  by  this  assumption, 
as  proven  later. 


34  NATURAL  GAS. 


While  the  gas  is  in  the  phosphorus  pipette  as  described  above,  oxygen  is 
drawn  into  the  burette  to  its  capacity,  the  capillary  is  filled  with  water,  and 
a  reading  is  taken.  The  gas  is  then  forced  into  the  explosion  pipette  until 
the  water  is  at  the  zero  mark,  the  capillary  containing  gas.  The  light  hand 
capillary  tube  is  flushed  with  water,  and  50  c  c.  of  air  are  drawn  into  the 
burette  and  measured;  about  15  c  c.  oxygen  (sufficient  to  make  the  total 
122  c  c.)  are  then  added,  and  the  gas  is  forced  into  the  explosion  pipette. 
The  right  hand  capillary  is  flushed  out,  and  the  gas  in  the  phosphorus  pipette 
is  drawn  into  the  burette  and  measured,  as  described  under  Determination 
of  Oxygen.  One-half  the  residue  is  discaided  or  reserved  in  the  phosphorus 
pipette.  About  10  c  c.  of  the  half  reserved  for  analysis  are  forced  into  the 
explosion  pipette  and  exploded.  This  operation  is  repeated  with  successive 
portions  of  the  gas  until  the  last  is  added,  when  the  gases  are  thoroughly 
mixed  before  explosion.  The  resultant  gas  is  very  rich  in  carbon  dioxide, 
which,  if  the  gas  were  passed  into  the  burette,  might  be  absorbed  by  the 
water.  Later  on  this  dissolved  carbon  dioxide  may  be  given  off  by  the 
water.  Therefore,  a  compressor  is  placed  on  the  rubber  tubing  from  the 
burette  to  the  bottle,  and  the  gas  in  the  explosion  pipette  is  forced  to  bubble 
through  the  potassium  hydroxide  pipette  by  raising  the  bottle  connected  to 
the  explosion  pipette.  After  the  gas  has  been  passed  several  times  it  is 
transferred  to  the  burette,  and  a  reading  is  taken.  The  sum  of  the  diluted 
oxygen  added  and  the  gas  residue  taken  for  explosion,  minus  the  volume 
remaining  after  the  absorption  of  carbon  dioxide,  is  Contraction  "A."  Hydro- 
gen is  then  added  to  the  capacity  of  the  burette,  a  reading  is  taken,  and  the 
gases  are  passed  into  the  explosion  pipette,  well  mixed  and  exploded.  The 
residue  is  passed  into  the  burette  and  measured,  the  decrease  in  volume  is 
Contraction  "C." 

From  the  above  contractions  ("A"  and  "C")  and  from  a  knowledge 
of  the  amount  of  oxygen  in  the  commercial  oxygen,  the  methane  and  ethane 
may  be  calculated.  The  reactions  of  burning  methane  and  ethane  are  as 
follows: 

CH4  +  2  O2  =  C02  +  2  H2O. 
2  C2He  +  7  O2  =  4  CO2  +  6  H2O 

From  these  reactions  it  is  seen  that  the  total  contraction  on  combustion  and 
absorption  of  methane  and  ethane  are  3  and  %  times   the  volume  of   the 


NATURAL  GAS. 


35 


respective  gases;  or  that  "A"  =  3  CH4  +  9/2  C2H6.  Likewise  the  oxygen 
consumed  (Oc)  is  2  and  %  times  the  volume  of  the  respective  gases;  or 
Oc  =  2  CH4  +  %  C2H6.  Also  it  is  evident  that  the  oxygen  consumed 
equals  the  oxygen  added  (Oa)  minus  the  oxygen  entering  the  second  explosion, 
which  is  %  C.  or  Oc  =  Oa  —  %  C. 

From  these  equations  the  following  formulae  are  derived: 

CH4  =  7/sA  +  C  —  3  Oa. 
C2H6  =  (A  +  y3  C  —  Oa)  —  CH4. 


Example — Data. 


Burette  Readings. 


Puiity  of  Oxygen. 
0.0 

Hydrogen  added 99.0      Hydrogen  added. 

99.0 
0.0 

Hydrogen  added 96.8      Hydrogen  added. 

96.8 
0.0 

Commercial  Oxygen  added 61.8      Commercial  Oxygen  added. 

61.8         257.6      Total  volume. 

Explosion 77.0      Residue. 

77.0         180.6      Contraction. 

60.2      %  Contraction  or  Oxygen. 
60.2  -*-  61.8  =  97.4%  Oxygen  in  Commercial  Oxygen. 
Gas  Analysis. 
100.0 

Potassium  Hydroxide . .2%  Carbon  Dioxide. 

99.8 

Palladium  Chloride .4%  Illuminants. 

99.4 

Stick  Phosphorus .0%  Oxygen. 

99.4 

49.7  Y2  Residue. 


36 


NATURAL  GAS. 


Gas  Analysis.                                                    Oxygen. 

0.0 

Commercial  Oxygen  

99.4      Commercial  Oxygen  ..   96.82 

99.4 

0.0 

Air 

50.0      Air  .  .            10.45 

50.0 

Commercial  Oxygen.  .  . 

15.0      Commercial  Oxygen.  .    14.61 

65.0                                                              121.88 

49.7      y2  Residue. 

Explosion  and  Absorption 

Hydrogen  added 

Explosion 


214.1  Total  volume. 

53.9  Residue. 

53.9         160.2  Contraction  "A." 

98.4 

67.7          30.7  Contraction  "C." 


Calculations. 

160.2      Contraction  A. 
X  7 
3/1121.4 

%  Contraction  A. 
Contraction  C. 


373.8 

30.7 

404.5 

365.64 

38.86 

160.2 

10.23 

170.43 

121.88 

48.55 

38.86 

9.69 


3  X  Oxygen  added. 
Methane. 

Contraction  A. 
^  Contraction  C. 

Oxygen  added. 
Total  Combustibles. 
Methane. 
Ethane. 


Analysis. 

\ 

Carbon  Dioxide 2% 

Illuminants .4% 

Oxygen 0% 

Methane 77.7% 

Ethane 19.4% 

Nitrogen 2.3% 

100.0% 


NATURAL  GAS.  37 


Determination  of  Hydrogen  and  Carbon  Monoxide.  These  gases  are 
generally  absent.  If  present,  they  reduce  palladium  chloride  somewhat 
slowly,  water  and  carbon  dioxide  being  formed.  If  the  diminution  in  volume 
caused  by  the  passage  of  the  gas  through  palladium  chloride  is  considerable, 
the  presence  of  hydrogen  or  carbon  monoxide  would  be  indicated,  in  which 
case  their  determination  is  advisable.  For  this  purpose,  the  apparatus  for 
supplying  hydrogen  is  disconnected,  and  a  palladium  tube  is  connected  to  the 
end  of  the  gas  apparatus, — the  other  end  of  the  palladium  tube  is  connected 
to  an  absorption  pipette  containing  water.  The  palladium  tube  is  immersed 
in  a  beaker  of  water  at  90-100  degrees  C.,  and  oxygen  is  passed  through  the 
tube  to  oxidize  any  hydrogen  present.  The  water  is  drawn  to  a  specified 
point  in  the  stem  of  the  absorption  pipette,  and  the  capillary  tube  of  the 
apparatus  is  filled  with  water  from  the  explosion  pipette.  Fifty  c  c.  of 
natural  gas  are  then  introduced  into  the  burette  and  measured,  the  carbon 
dioxide  is  removed,  and  the  gas  is  passed  through  fuming  sulphuric  acid. 
About  10  c  c.  of  oxygen  are  added,  and  a  reading  is  taken.  The  gases  are 
then  passed  back  and  forth  through  the  palladium  tube,  whichis  immersed  in 
hot  water  at  first  and  then  in  cold  water  to  cool  the  gas.  The  gas  is  finally 
brought  back  into  the  burette,  the  water  in  the  pipette  being  at  the 
previous  level,  and  a  reading  is  taken.  The  decrease  in  volume  is  noted 
as  Contraction  "a."  The  gases  are  then  passed  into  potassium  hydroxide, 
drawn  back  and  measured;  the  diminution  in  volume  is  Contraction  "b." 
From  a  study  of  the  contractions  formed  in  the  combustion  of  carbon  monoxide 
and  hydrogen,  it  is  seen  that 

C0  =  b 
2a  —  b 
3 

Error  in  Assuming  the  Gas  to  be  Methane  and  Ethane.  The  basis  of  the 
determination  is  in  reality  the  volume  of  combustible  gas  (equal  to  A — 
Oxygen  consumed)  and  the  oxygen  necessary  for  combustion  (Oxygen  con- 
sumed =  Oxygen  added — H  C).  Both  are  accurately  determined,  con- 
sequently the  combustibles  present  and  the  amount  of  air  necessary  for 
their  combustion  as  calculated  from  the  analysis  is  correct.  The  carbon 
dioxide  formed  on  combuscion  has  not  been  determined  but  can  be  calculated 
for  any  and  all  paraffines  which  have  the  general  formula  Cn  H2n  +  2-  If  n 
represents  the  number  of  carbon  atoms  in  the  molecule,  and  p  the  total 


38  BENZOL  IN  BY-PRODUCT  GAS. 

volume  of  paraffines,  then,  by  reasoning  analogous  to  that  given  when  the 
formulae  were  derived,  np  equals  (Oxygen  consumed  —  H  A).  But  np 
equals  the  carbon  dioxide  and  is  independent  of  any  particular  paraffines 
that  may  be  assumed  to  be  present,  therefore,  the  carbon  dioxide  formed  on 
the  combustion  of  the  gas,  as  calculated  from  the  analysis,  is  correct.  As 
regards  the  heat  value  calculated  from  the  analysis,  Thomsen  has  shown 
that  the  heat  value  of  a  paraffine  is  equal  to  K  +  nD  where  K  and  D  are 
constant  factors.  The  heating  value  of  the  unabsorbed  portions  of  natural 
gas  then  is  (K  +  nD)  p  or  Kp  +  Dnp.  It  has  been  shown  that  p  and  np 
are  correct,  depending  upon  the  factors  A,  C  and  Oa.  Therefore,  the  heating 
value  of  natural  gas  as  calculated  from  the  analysis  is  correct. 

BENZOL  IN  BY-PRODUCT  GAS. 

Unwashed  by-product  gas  contains  about  .8%  to  1.0%  benzol,  and 
the  washed  gas  contains  about  .2%.  It  is  determined  by  passing  the  gas 
through  paraffine  oil  in  a  series  of  bottles  and  distilling  the  absorbed  benzol 
as  described  on  Page  80  of  the  "Coal,  Coke  and  By-Product"  pamphlet. 
The  result  so  obtained  is  converted  into  pounds  and  divided  by  the  number 
of  cubic  feet  of  gas  at  standard  temperature  and  pressure.  This  result, 
when  divided  by  the  weight  of  a  cubic  foot  of  benzol  (gas)  at  62  degrees  and 
30  inches  (Table  "A")  and  multiplied  by  100,  gives  the  percentage.  This 
percentage  is  subtracted  from  the  illuminants  as  obtained  by  volumetric 
analysis,  the  difference  being  ethylene  and  possibly  its  homologues. 

Example: 

Gas  metered  (reduced  to  Standard  conditions)  .  .  .=  75.4  Cubic  Feet. 

Benzol  obtained =      .152  Pounds. 

Benzol  per  Cubic  Foot =      .002016  Pounds. 

Per  cent,  of  benzol  (.002016  •*•  .21152  x  100)  .  .  .  .=      .95% 

TOTAL  SULPHUR  IN  BY-PRODUCT  GAS. 

The  sulphur  occurring  as  hydrogen  sulphide  is  removed  and  determined 
by  absorption  in  an  acetic  acid  solution  of  lead  acetate;  the  sulphur  otherwise 
combined  and  known  as  organic  sulphur  is  burnt  with  the  gas  in  a  Referees 
apparatus  and  determined  as  barium  sulphate.  The  train  consists  of  a  gas 
meter,  three  gas  washing  bottles,  containing  each  100  c.  c.  of  a  solution  of 


SULPHUR  IN  BY-PRODUCT  GAS.  39 

lead  acetate,  and  a  Referees  apparatus.  The  chimney  and  condenser  of  the 
Referees  apparatus  are  rinsed  with  water  and  as  much  ammonium  carbonate 
as  will  find  place  around  the  pillar  of  the  burner  is  added.  The  meter  reading, 
temperature,  barometer  and  manometer  readings,  and  time  are  taken.  The 
burner  is  lighted,  and  as  soon  as  the  flame  is  adjusted,  the  trumpet  tube  is 
connected  to  the  condenser.  The  gas  is  burned  at  the  rate  of  about  half  a 
cubic  foot  per  hour  for  a  period  of  from  two  to  four  hours.  The  condensate 
from  the  chimney,  condenser  and  trumpet  is  rinsed  into  the  collecting  breaker 
and  filtered.  Sulphur  is  determined  by  acidification  of  the  solution  with 
hydrochloric  acid  and  precipitation  as  barium  sulphate  with  barium  chloride. 
The  precipitate  is  removed  by  filtration,  ignited  and  weighed;  13.73%  of  its 
weight  is  sulphur. 

The  wash  bottles  contain  a  precipitate  of  lead  sulphide,  which  is  collected 
on  a  filter,  washed  with  hot  water,  and  dissolved  in  nitric  acid  into  a  volumetric 
flask.  The  solution  is  diluted  to  a  definite  volume,  then  an  aliquot  part  is 
withdrawn,  heated  to  boiling  and  10  c  c.  of  dilute  sulphuric  acid  (1:1)  are 
added.  Boiling  is  continued  for  about  30  minutes  and  the  precipitate  of 
lead  sulphate  is  allowed  to  cool,  when  it  is  removed  by  filtration,  washed, 
dried,  and  weighed;  10.57%  of  this  weight  is  sulphur,  and  11.24%  of  it  is 
the  equivalent  in  hydrogen  sulphide.  The  lead  acetate  solution  is  made 
by  dissolving  100  grams  lead  acetate  in  a  liter  of  water  containing  30  c  c.  of 
glacial  acetic  acid. 

Hydrogen  Sulphide  in  By-Product  Gas.  When  hydrogen  sulphide  alone 
is  to  be  determined,  use  is  made  of  the  following  method :  The  gas  is  aspirated 
through  two  wash  bottles  of  300  c  c.  capacity,  each  containing  100  c  c.  of 
a  5%  solution  of  sodium  hydroxide,  into  a  gasometer  of  about  15  liters  capa- 
city. A  large  aspirator  bottle,  graduated  to  200  c  c.  may  be  conveniently 
employed  as  a  gasometer.  The  top  opening  of  the  aspirator  bottle  is  closed 
with  a  large  three-holed  rubber  stopper  for  a  gas  inlet,  manometer  and  ther- 
mometer. Through  a  one-hole  rubber  stopper,  fitted  into  the  bottom  outlet 
of  the  gasometer,  is  placed  one  end  of  a  one-fourth  inch  glass  tube  bent  sharply 
at  right  angles  and  provided  on  the  other  end  with  a  short  rubber  tube,  on 
which  is  a  pinchcock  to  regulate  the  flow  of  water  from  the  gasometer  into 
the  receiver  below. 

About  ten  liters  of  gas  are  passed,  the  temperature  and  the  pressure  being 
recorded.  The  sodium  hydroxide  solutions  are  rinsed  into  a  liter  flask,  made 
up  to  a  definite  volume,  and  an  aliquot  part  taken  for  titration.  Ten  cubic 


40  SULPHUR  IN  BY-PRODUCT  GAS. 

centimeters  of  starch  solution  and  10  c  c.  of  a  .2%  solution  of  potassium 
iodide  are  added,  followed  by  dilute  hydrochloric  acid.  The  liberated  hydro- 
gen sulphide  is  titrated  with  standard  iodine  or  iodate  solution  to  the  first 
permanent  blue.  The  iodide  is  added  to  prevent  the  necessity,  otherwise, 
of  determining  and  deducting  a  blank.  The  starch  solution  is  made  as 
follows:  Five  grams  starch  (preferably  soluble  starch)  are  stirred  into  25  c  c. 
of  water,  and,  while  stirring  is  continued,  5  c  c.  of  a  solution  containing  2.5 
grams  sodium  hydroxide  are  added;  the  gelatinous  mass,  after  having  stood 
one  hour,  is  poured  into  water  and  diluted  to  one  liter.  Starch  may  also  be 
made  by  boiling,  as  described  in  the  Corporation  pamphlet  on  analysis  of 
steel. 

The  standard  iodine  solution  may  be  a  deci-normal  one  or  the  same 
solution  as  is  used  in  the  titration  of  sulphur  in  steel.  The  latter  solution 
is  made  by  dissolving  4  grams  iodine  and  10  grams  potassium  iodine  in  25 
c  c.  cold  water;  the  deci-normal  solution  is  made  by  dissolving  12.7  grams 
iodine  and  30  grams  potassium  iodide  in  75  c  c.  water.  When  solution  is 
complete,  water  is  added  to  a  volume  of  one  liter.  A  solution  of  potassium 
iodate  may  be  used  instead  of  the  iodine.  It  is  made  by  dissolving  1.112 
grams  iodate  and  6  grams  potassium  iodide  in  one  liter  of  water.  This 
solution  and  the  iodine  solution,  containing  4  grams  per  liter,  is  such  that 
Ice.  equals  .0005  gram  sulphur  and  .0005314  gram  or  .00820  grain 
hydrogen  sulphide.  One  cubic  centimeter  of  deci-normal  solution  equals 
.0017038  gram  or  .0263  grain  hydrogen  sulphide. 

The  volume  of  gas  measured  is  corrected  for  temperature  and  pressure 
as  subsequently  described,  and  the  resultant  number  of  cubic  feet  of  gas  at 
standard  temperature  and  pressure  is  divided  into  the  grains  of  hydrogen 
sulphide  found  by  titration;  the  result  should  also  be  stated  in  percentage. 
One  cubic  foot  of  hydrogen  sulphide  gas  weighs  636  grains,  therefore,  the 
grains  of  hydrogen  sulphide  found  per  100  cubic  feet,  divided  by  636,  gives 
the  percentage. 

Example: 

Gas  corrected  to  standard  conditions 382  Cubic  Foot. 

Iodate  used  in  titrating  an  aliquot  of  M> 22.4       c  c. 

Iodate  equivalent  to  total  sulphide 112.0       c  c. 

Hydrogen  sulphide  present  (.00820  x  112.) 9184  Grain. 


CYANOGEN  IN  BY-PRODUCT  GAS.  41 

Hydrogen  sulphide  per  100  cubic  feet 

(.9184  H-  .382  X  100) 240.          Grains 

Hydrogen  sulphide  by  volume  (240.  4-  636) 38% 

An  alternative  method  consists  in  titrating  the  gas  direct  with  a  standard 
solution  of  iodine.  One  hundred  c  c.  of  gas  are  drawn  into  a  suitable  pipette 
containing  starch  solution,  and  iodine  is  added  until  a  permanent  blue  is 
obtained.  The  iodine  solucion  is  made  by  dissolving  1.7076  grams  of  iodine 
and  20  grams  potassium  iodide  in  25  c  c.  water  and  diluting  to  one  liter; 
1  c  c.  of  this  solution  used  in  titrating  100  c  c.  of  gas  is  equivalent  to  100 
grains  of  hydrogen  sulphide  per  100  cubic  feet  of  gas. 

CYANOGEN  IN  BY-PRODUCT  GAS. 

In  this  determination  the  cyanogen  is  converted  into  potassium  ferro- 
cyanide  by  being  passed  through  a  potassium  hydroxide  solution  containing 
freshly  precipitated  ferrous  hydroxide  in  suspension.  After  nitration,  the 
potassium  ferro-cyanide  is  determined  in  the  clear  solution  by  acidification 
and  titration  with  a  standard  solution  of  ferric  chloride. 

Into  each  of  three  wash  bottles  are  placed  60  c  c.  of  a  10%  potassium 
hydroxide  solution  and  30  c  c.  of  a  ferrous  sulphate  solution  (10%  of  the 
crystals).  Gas  is  passed  at  the  rate  of  two  to  three  cubic  feet  per  hour  for 
about  four  hours.  The  precipitate  and  solution  are  transferred  from  the  wash 
bottles  to  a  600  c  c.  beaker,  and  boiled.  The  solution  is  filtered  while 
hot  into  a  volumetric  flask,  and  the  precipitate  washed,  the  washing  going 
also  into  the  flask.  An  aliquot  part  of  the  filtrate  is  transferred  to  a  beaker 
and  one  drop  of  ferric  chloride  solution  is  added,  followed  by  the  careful 
addition  of  dilute  sulphuric  acid  until  the  resultant  precipitate  just  dissolves. 
The  solution  is  now  titrated  with  standard  ferric  chloride  solution.  The 
end  point  of  the  titration  is  indicated  by  the  spot  test ;  a  few  drops  from  the 
beaker  containing  the  liquid  under  titration  are  placed  on  a  white  filter  paper; 
a  spot  will  be  formed  with  the  blue  already  precipitated  surrounded  by  a 
circle  of  the  clear  solution.  When  neither  ferric  chloride  solution  nor  potas- 
sium ferro-cyanide  solution  cause  a  blue  color  upon  being  placed  on  the  clear 
circle,  the  end  point  is  reached. 

The  ferric  chloride  solution  is  made  by  dissolving  25  grams  of  the  salt 
in  water,  acidified  slightly  with  hydrochloric  acid,  and  diluting  to  1  liter.  It 
is  standardized  by  titrating  with  a  standard  solution  of  potassium  ferro- 


42  STANDARD  TEMPERATURE  AND  PRESSURE. 

cyanide  made  by  dissolving  4.22  grams  of  K4Fe  (CN)e  +  3  H2O  in  1  liter 
of  water.  One  hundred  c  c.  of  this  solution  are  withdrawn  with  a  pipette, 
transferred  to  a  beaker,  and  titrated  as  described  above;  this  aliquot  part  is 
equal  to  0.156  grams  of  cyanogen.  The  cubic  feet  of  gas  as  metered  is 
corrected  for  pressure,  temperature  and  moisture  as  hereafter  described. 


REDUCTION  OF  VOLUME  TO   STANDARD   TEMPERATURE   AND 
PRESSURE. 

In  the  determination  of  benzol,  cyanogen  or  calorific  value  of  a  gas,  a 
wet  meter  or  tank  is  used  for  measuring  the  gas,  and  the  temperature  and 
pressure  at  the  meter  or  tank  are  taken,  so  that  the  volume  metered  may 
be  reduced  to  standard  conditions  of  temperature  and  pressure.  However, 
the  gas  is  saturated  with  moisture  which  has  a  definite  partial  pressure. 

To  reduce  the  gas  volume  to  dry  gas  under  standard  conditions,  the 
procedure  is  the  same  as  if  dry  gas  were  metered,  except  that  the  pressure 
of  the  dry  gas  is  found  by  subtracting  the  vapor  pressure  from  the  total 
pressure  of  the  mixture  of  gas  and  vapor. 

Let  Vs=  Volume  of  dry  gas  at  62°  F.  and  30"  mercury. 
V  =  Volume  as  metered. 
b  =  barometer  in  inches  of  mercury, 
p  =  pressure  of  meter  in  inches  of  mercury, 
e   =  vapor  pressure  in  inches  of  mercury  at  temperature  of  meter, 

as  given  in  Table  (B). 

t    =  temperature  in  Fahrenheit  of  the  meter. 
(0°  F.  is  considered  459°  Absolute.) 

The  pressure  of  the  mixture  of  water  vapor  and  dry  gas  in  the  meter 
is  (b  +  p),  and  since  the  pressure  of  water  vapor  is  (e),  the  pressure  due  to 
dry  gas  is  (b  +  p  —  e). 

-ru       t          ^7          w    v        521        v  b  +  P  — e 
Therefore,  Vs  =  V  X  X 

459  +  t  30 

The   calculation    may   be    simplified    by    applying    a    factor    equal    to 

X as  found  in  Table  C.     This  table  gives  the  factor  for 

459  +  t  30 

reducing  a  given  volume  of  gas  to  62°  F.  and  30"  Mercury. 


THERMAL   VALUES.  43 


Example: 

Barometer  reading  (b)  .......................  =29.40" 

Pressure  of  meter  (p)  ........................  =  3.5"  Water. 

Vapor  pressure  at  70°  F.  (e,  Table  "B")  .......  =     .73"  Mercury. 

Temperature  of  meter  (t)  ....................  ==70°  Fahrenheit. 

Gas  measured  .......  .......................  =  2.813  Cubic  Feet. 

Inches  of  water  is  converted  to  inches  of  mercury  by  multiplying  by 
.0738. 

3.5  x  .0738  =  .26"  Mercury,  pressure  of  meter. 

Pressure  of  dry  gas  is  29.40"  +  .26"  —  .73"  =  28.93"  and  the  volume 
of  dry  gas  at  standard  temperature  and  pressure  equivalent  to  the  wet 
gas  metered  is,  therefore, 


2.8X3   x  X  _  2.672. 

529  30 

Using  Table  "C,"  the  factor  for  70°  and  28.93"  is  found  to  be  .9498. 
2.813  x  .9498  =  2.672  cubic  feet  of  dry  gas. 

THERMAL  VALUES: 

The  thermal  values  may  be  determined  by  calorimeter  or  by  calculation 
from  the  gas  analysis.  Considerable  variations  exist  among  the  values 
commonly  given  as  heats  of  combustion  for  the  different  gases;  but  it  is 
believed  that  the  following  figures,  calculated  from  Thomsen,  will  give  results 
which  are  sufficiently  reliable  tor  all  technical  purposes.  In  Column  III  of 
Table  "A,"  showing  the  British  thermal  units  developed  in  the  combustion 
of  one  cubic  foot  of  the  different  gases,  measured  at  62°  F.  and  30"  Mercury, 
two  values  are  given  —  the  gross  and  the  net  —  the  difference  between  them 
being  the  latent  heat  of  the  water  formed,  which  is  not  included  in  the  latter. 
The  temperature  of  the  products  of  combustion  in  both  cases  are  assumed 
to  be  62°  F.  For  the  purpose  of  comparison,  all  Corporation  results  should 
be  expressed  in  terms  of  Net  B.  t.  u.  Where  the  illuminants  contain  gases 
having  a  higher  heat  value  than  ethylene,  a  higher  value  should  be  used,  this 
being  determined  from  the  gas  by  analysis.  The  peicentage  of  each  com- 
bustible present  is  multiplied  by  its  value  in  the  table,  and  the  sum  of  the 
products  will  represent  the  British  thermal  units  evolved  in  the  combustion 
of  one  cubic  foot  of  the  gas. 


44  WEIGHT  OF  A   CUBIC  FOOT  OF  GAS. 

Example: 

Gas  Analysis.  Thermal  Value. 

Carbon  Dioxide. 4.5 

Illuminants 5%  of  1495  =      7.48  B.  t.  u. 

Oxygen 0.0 

Carbon  Monoxide 25.8%  of  322    =    83.08  B.  t.  u. 

Methane 2.8%  of  909    =    25.45  B.  t.  u. 

Hydrogen 12.6%  of  274    =    34.52  B.  t.  u. 

Nitrogen 53.8%  150.5    B.  t.  u. 


WEIGHT  OF  A  CUBIC  FOOT  OF  GAS. 

Column  II  of  Table  "C"  shows  the  weight  in  pounds  of  a  cubic  foot  of 
the  constituent  gases  at  a  temperature  of  62°  F.  and  a  pressure  of  30"  mercury. 
The  weight  of  a  cubic  foot  of  gas  is  the  sum  of  the  values,  found  by 
multiplying  the  weight  per  cubic  foot  of  each  of  the  constituent  gases  by 
its  percentage  of  volume.  The  weight  of  a  cubic  foot  of  moist  gas  is  found 
by  adding  the  weight  of  the  cubic  foot  of  dry  gas  at  its  temperature  and 
partial  pressure  to  the  weight  of  a  cubic  foot  of  water  vapor  at  its  partial 
pressure. 

Example: 

Gas  has  been  washed  at  70°  and  29.66"  and  was,  therefore,  satuiated. 
Pressure  of  moisture  is  .73",  pressure  of  dry  gas  is  29.66  —  .73  =  28.93". 

Gas  Analysis. 

Carbon  Dioxide 13.0%  of  .11671  =  .015172 

Carbon  Monoxide 25.8%  of  .07365  =  .019002 

Hydrogen 3.8%  of  .00531  =  .000202 

Nitrogen 57.4%  of  .07368  =  .042292 

Weight  of  1  cubic  foot  dry  gas  at  62°  and  30"  =.07667  Pound. 

X. 9498  (See  Table  "C") 

Weight  of  1  cubic  foot  dry  gas  at  70°  and  28.93"  =.07282  Pound. 
Weight  of  1  cubic  foot  moisture  at  70°  and  .73"  = 

(Table  B)  is  7.98  Grains  or  .00114  Pound. 

Weight  of  1  cubic  foot  wet  gas  at  70°  and  29.66"=.07396  Pound. 


SPECIFIC  GRAVITY  AND  PERCENTAGE  BY  WEIGHT.        45 

By  another  method  the  weight  of  a  cubic  foot  of  wet  gas  is  found  by 
adding  the  weight  of  a  cubic  foot  of  dry  gas  to  the  weight  of  moisture  accom- 
panying it  and  dividing  the  sum  by  one,  plus  the  volume  of  moisture  accom- 
panying one  cubic  foot  dry  gas;  this  latter  volume  is  found  by  multiplying 
the  grains  of  moisture  by  .00301,  the  volume  occupied  by  one  grain  of  moisture 
at  62°  and  30". 

Example: 

The  gas  contains  6  grains  of  moisture  per  cubic  foot  at 

62°  and  30". 
Conditions  in  the  main  were  70°  and  29.66". 

Weight  of  1  cubic  foot  of  dry  gas  at  62°  and  30" =.07667  Pound. 

At  62°  and  30",  1  cubic  foot  of  water  vapor  theoretically 

weighs    .04749    pound    from    which    one   grain   would 

occupy  .00301  cubic  foot. 

Volume  of  moisture=6  x  .00301  =  .01806  cubic  foot. 
Weight  of  .01806  cubic  foot  Moisture 

(.01806  x  .04749  or  6  -*-  7000) . .  .  .=.00086  Pound. 


Weight  of  1.01806  cubic  feet  moist  gas =.07753  Pound. 

Weight  of  1  cubic  foot  of  moist  gas  at  62°  and  30" =.07615  Pound. 

Weight  of  1  cubic  foot  of  moist  gas  at  70°  and  29.66".— 

(.07615  x  .9737)   (See  Table  C) =.07415  Pound. 

Specific  Gravity  and  Percentage  by  Weight.  When  suitable  apparatus 
is  not  available  for  determining  the  specific  gravity  of  gas,  it  may  be  calculated 
from  the  volumetric  analysis  by  means  of  Column  I  of  Table  "A,"  showing 
the  specific  gravity  of  various  gases  compared  with  air.  The  calculated 
specific  gravity  of  a  gas  is  found  by  adding  the  products  obtained  by  multi- 
plying the  percentage  by  volume  of  each  constituent  gas  by  its  specific  gravity. 
The  respective  products  thus  obtained,  divided  by  the  specific  gravity  of  the 
gas,  yield  the  percentage  by  weight  of  the  constituent  gases. 

The  specific  gravity  of  moist  gas  is  found  by  adding  the  product  of  .6221 
and  the  percentage  of  water  vapor  accompanying  dry  gas  to  the  specific 
gravity  of  the  dry  gas,  and  dividing  the  sum  by  one,  plus  the  percentage  of 
water  vapor.  This  latter  value  is  found  by  multiplying  the  grains  per  cubic 
foot  dry  gas  by  .00301,  the  volume  occupied  by  1  grain  water  vapor. 


46  THE  AIR  NECESSARY  FOR  COMBUSTION. 

Example: 

Gas  Analysis. 

Carbon  Dioxide 13.0%  of  1.5288  =    .19874 

Oxygen 0% 

Carbon  Monoxide 25.8%  of    .9648  ==    .24892 

Methane 0% 

Hydrogen 3.8%  of    .0695  ==    .00264 

Nitrogen 57.4%  of    .9651  ==    .55397 

Specific  gravity  of  dry  gas '. =  1.0043 

Moisture  on  this  gas  was  found  to  be  6  grains  per  cubic  foot  dry  gas  at 
62°  and  30".  Volume  of  moisture  was,  therefore,  6  X  .00301  or  .01806 
cubic  foot. 

Therefore,  specific  gravity  of  dry  gas =  1.0043 

.01806  cubic  foot  moisture  at  .6221  specific  gravity =    .0112 


1.0155 

. 

Specific  gravity  of  moist  gas  is  1.0155  •+-  1.01806 =  .9975 

The  specific  gravity  of  gas  over  water  varies  with  the  temperature  since 
the  amount  of  water  taken  up  varies. 

APPENDIX. 

The  Air  Necessary  for  Combustion.  Column  IV  of  Table  "A"  gives 
the  amount  of  oxygen  necessary  for  combustion  of  the  various  gases.  It 
may  be  repeated  here  and  stated  as  an  equation,  thus: 

Oxygen  Necessary,  (On)  =  3  C2H4  +  .5  CO  +  2  CH4  +  .5  H2  +  3.5 
C2H6  +  7.5  C6H6-02. 

Air  is  composed  of  20.9%  oxygen,  the  remaining  79.1%  being  considered 
nitrogen.  The  nitrogen  is  then  3.78  times  the  oxygen,  and  the  air 
necessary  for  combustion  is  4.78  times  the  oxygen.  The  above  is  in  terms  of 
cubic  feet  of  dry  air  per  cubic  foot  of  dry  gas  at  the  same  temperature  and 
pressure. 

The  Products  of  Combustion.  The  products  are  given  in  Table  "A", 
Column  V.  Placed  as  equations,  they  are: 

CO2  produced  =  CO2  +  CO  +  CH4  +  2  C2H4  +  2  C2H6  +  6  C6  H  e 
H2O  produced  =  H2  +  2  CH4  +  2  C2H4  +  3  C2H6  +  3  C6H6. 


THE  PRODUCTS  OF  COMBUSTION. 


47 


N2  produced  =  N2  +  3.78  (3  C2H4  +  .5  CO  +  2  CH4  +  .5  H2  + 
3.5  C2H6  +  7.5  C6H6  —  O2).  The  volumes  above  refer  to  volumes  per  dry 
volume  of  fuel  gas,  and  the  moisture  in  the  fuel  gas  and  in  the  air  must  be 
added. 


Example: 

Gas  Analysis 

Carbon  Dioxide. .  .  . 

Ethylene 

Benzine 

Carbon  Monoxide.  . 

Methane 

Hydrogen 

Nitrogen 

Oxygen 


90.45% 
N2  produced  is  10.9  +  3.78  X  90.45 


Percent- 

Oxygen 

age 

Necessary 

-      1-8% 

0.0       ' 

.     2.2% 

6.6 

.       .2% 

1.5 

.     4.8% 

2.4 

26.8% 

53.6 

.   53.1% 

26.55 

.    10.9% 

90.65 

.        .2% 

.2 

Products  of  Combustion. 
CO*  H9O  No 


1.8 
4.4 
1.2 

4.8 
26.8 


4.4 
.6 

53.6 
53.1 


39.0% 


111.7% 


352.80 


Air  necessary=4.78  X  90.45  =  432.35%  or  4.3235  cubic  feet  per  cubic 
foot  of  dry  fuel  gas  at  same  temperature  and  pressure. 

The  moisture  in  fuel  gas  was  found  to  be  6  grains  per  cubic  foot  at  62° 
and  30-",  therefore,  its  volume  is  6  X  .3  =  1.8%  of  the  dry  fuel  gas.  The  air 
contains  4  grains  per  cubic  foot;  from  Table  "B"  it  is  found  that  4  grains 
compare  with  .35"  pressure,  therefore,  the  pressure  of  air  is  the  barometric 
pressure  (29.40")  minus  .35"  or  29.05."  The  volume  of  moisture  is  .35 
-5-  29.05  X  100=  1.2%  of  the  dry  air.  The  total  moisture  is  then  111.7  + 
1.8  +  (1.2%  of  432.35)  =  118.7%  of  the  fuel  gas  or  1.187  cubic  feet  per  cubic 
foot  of  dry  fuel  gas,  measured  at  the  same  temperature  and  pressure. 


The  products  are  summarized  as  follows: 


CO2. 

N2.. 
H20 


.  .  39.0%  of  fuel  gas. 
.  .352.8%  of  fuel  gas. 
.  .118.7%  of  fuel  gas. 


48  COMPOSITION  OF  PERFECT  FLUE  GAS. 

Composition  of  Perfect  Flue  Gas.  The  above  figures  show  the  products 
of  perfect  combustion  of  a  volume  of  fuel  gas.  Their  percentages  of  the  flue 
gas  are  easily  calculated  by  dividing  each  by  the  sum. 

Flue  Gas  Dry  Moist 

CO2  10.0%  7.6% 

N2  90.0%  69.1% 

H20  23.3% 


100.0%  100.0% 

For  the  purposes  of  comparison,  data  are  given  for  the  other  fuel  gases. 

Blast  Furnace  Gas  Natural  Gas 

CO2  25.6%  12.1% 

N2  74.4%  87.9% 

100.0%  100.0% 

The  products  of  combustion  from  burning  pure  carbon  would  contain 
20.9%  carbon  dioxide,  since  it  has  the  same  volume  as  the  oxygen  used. 
The  dry  products  of  combustion  of  coals  contain  less  CO2  than  20.9  due  to 
the  fact  that  the  hydrogen  of  the  coals  requires  oxygen  from  the  air,  resulting 
in  more  nitrogen  than  if  pure  carbon  were  burnt.  The  percentages  of  carbon 
dioxide  in  the  products  of  combustion  resulting  from  perfect  combustion  of 
various  coals  have  been  calculated  and  are  given  here  for  comparison. 

Anthracite  Culm,  Scianton,  Pa 19.5%  CO2 

Semi-Anthracite,  Coalhill,  Ark 19.0%     " 

Semi-Bituminous,  Mora,  W.  Va ^ 18.8% 

Bituminous  Coking,  Connellsville,  Pa 18.8% 

Bituminous  Non-Coking,  Hocking  Valley,  Ohio 18.7% 

Sub-Bituminous,  Unita  Co.,  Wyo 18.9%     " 

Lignite,  Milan  Co.,  Texas 19.2%     " 

Producer  gas  being  derived  from  coal  by  partial  combustion,  the  ultimate 
products  of  combustion  (dry)  are  the  same  as  if  coal  were  used  for  fuel. 

Excess  Air.  The  complete  combustion  of  a  fuel  with  the  proper  amount 
of  air  is  rarely  obtained.  In  practice  there  is  generally  an  excess  of  air  and 
also  incomplete  combustion,  some  carbon  monoxide  being  found  in  the  flue 
gas.  This  carbon  monoxide  should  have  combined  with  oxygen  present 


EXCESS  AIR.  49 


forming  carbon  dioxide,  according  to  the  equation:  2  CO  +  O2  =  2  CO2. 
The  oxygen  which  should  have  combined  is  one-half  the  volume  of  the  carbon 
monoxide,  the  excess  oxygen  is  then  O2'  —  K  CO'  (to  prevent  confusion, 
prime  [']  is  placed  over  the  formulae  of  the  various  flue  gases).  The  excess 

(V  —  \/2  CO' 

air  is  — stated  as  percentage  of  the  flue  gas.      The  excess  air, 

.209 

however,  is  usually  stated  as  percentage  of  the  air  required  or  necessary. 
This  is  calculated  from  the  nitrogen  as  follows:  The  excess  nitrogen  or 
NX  is  3.78  times  the  excess  oxygen  Ox  or 

(1)  NX  =  3.78  (02'  —  ^  CO') 

A  flue  gas  is  composed  of  two  parts,  the  excess  air  and  the  perfect  flue  gas, 
consequently,  the  nitrogen  of  perfect  flue  gas  (Nt),  plus  the  nitrogen  of 
excess  air  (Nx)  equals  the  nitrogen  of  the  flue  gas  (N2')  from  which  Nt  =N9' 
—  NX.  By  substitution  for  NX,  its  value  shown  in  equation  (1),  the  following 
is  obtained: 

(2)  Nt  =  N2'  —  3.78  (O2'  —  Y2  CO') 

By  dividing  equation  (1)  by  (2),  a  proportion  is  obtained, 

Nx_         3.78  (02'  — 

(3)  = 


Nt        N2'  —  3.78  (O2'  —  Yz  CO') 
In  burning  a  fuel  containing  no  nitrogen,  the  nitrogen  of  perfect  flue 
gas  (Nt);  coming  only  from  air,  is  the  nitrogen  of  air  necessary  for  complete 
combustion  (Nn).     Therefore,  substituting  for  Nt  in  equation  (3)  its  equal 
Nn,  the  equation  is  derived: — 

NX  3.78  (Oo'  —  y*  CO') 

(4)     —  = 


Nn  N2'  —  3.78  (O2'  —  ^  CO') 
This  is  the  ratio  of  excess  nitrogen  to  necessary  nitrogen,  and  is  the  same  as 
the  ratio  of  excess  air  to  necessary  air.  Coal  contains  a  small  amount  of 
nitrogen,  but  the  error  introduced  is  negligible,  and  the  foregoing  formula 
multiplied  by  100  shows  the  percentage  of  excess  air,  using  coal  as  a  fuel. 

However  in  burning  a  gaseous  fuel  containing  nitrogen,  another  factor 
is  introduced,  and  the  formula  is  more  complicated.  For  a  fuel  gas  the 
nitrogen  from  air  necessary  for  combustion  is  3.78  times  the  oxygen  (On), 
which  value  was  given  under  "Air  Necessary  for  Combustion." 
(5)  Nn  =  3.78  times  On.  The  nitrogen  of  perfect  flue  gas  (Nt)  equals  the 
sum  of  the  nitrogen  of  the  original  gas  (N2)  and  the  nitrogen  of  air  necessary 


50  CORRECTNESS  OF  SAMPLING  AND  ANALYSIS. 

for  complete  combustion  (Nn)  or  Nt  =  N2  +  Nn,  from  which, 

(6)  Nt  =  N2  +  3.78  times  On.      Now,  if  equation  (3)  be  multiplied  by  the 
quotient  of  (6),  divided  by  (5),  a  proportion  referring  to  excess  nitrogen  results: 

NX  3.78  (O2'  —  1A  CO')  N2  +  3.78  On 

(7)  —  =•• — ~~ X 

Nn       N2'  —  3.78  (O2'  —  M  CO')  3.78  On 

NX  to  Nn  is  the  ratio  of  excess  nitrogen  to  necessary  nitrogen  and  is  the  same 
as  the  ratio  of  excess  air  to  necessary  air.  It  is  noted  that  the  first  fraction 
refers  to  the  flue  gas  alone,  and  the  second  fraction  to  the  fuel  gas  and  is 
fairly  constant  for  any  given  fuel. 

Example: 

Flue  Gas  Analysis. 

Carbon  Dioxide 5.2% 

Oxygen 8.7% 

Carbon  Monoxide 8% 

Nitrogen 85.3% 

100.0% 

This  flue  gas  was  derived  from  combustion  of  the  by-product  gas  given  in 
example  under  "The  Products  of  Combustion." 
Excess  Oxygen  =  8.7  —  .4  =  8.3%  of  flue  gas. 

Oxygen  necessary  for  combustion  =  90.45%  of  fuel  gas  previously  given. 
Ratio  of  excess  air  to  necessary  air  = 

3.78  X  8.3  10.9  +  3.78  X  90.45 

X  -  -  =  58.2%  X  1.032  =  60.1% 


85.3  —  3.78  X  8.3  3.78  X  90.45 

Correctness  of  Sampling  and  Analysis.  As  stated  before,  the  flue  gas 
may  be  considered  as  composed  of  excess  air  and  of  perfect  flue  gas;  the  sum 
of  the  two  should  equal  100%  less  the  diminution  in  volume  caused  by  con- 
traction in  volume  if  the  CO  were  completely  burnt;  or,  if  (CO2t)  repiesents  the 
carbon  dioxide  of  perfect  flue  gas,  then. 

CO2'  +  CO'        <V  —  K  CO' 

-  +  —  -  +  1A  co'  =  100% 

CO2t  .209 

Example:  Flue  gas  cited  under  "Excess  Air"  and  by-product  gas  under 
"Products  of  Combustion." 

5.2  +  .8        8.7  —  .4 

-   +  -  +  .4  =  100.1% 

.10  .209 


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UT 


UNIVERSITY  OF  CALIFORNIA  LIBRARY 
BERKELEY 


Return  to  desk  from  which  borrowed. 
This  book  is  DUE  on  the  last  date  stamped  below. 


9!Ylar'5CHJ 


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I/D  21-100m-ll,'49(B7146sl6)476 


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UNIVERSITY  OF  CALIFORNIA  LIBRARY 


